Cryptologic Aspects of the Atterbury Plot

The so-called Atterbury Plot aimed to replace the Hanoverian King George I with the Stuart Pretender. Francis Atterbury, Bishop of Rochester, was arrested in August 1722 and by the proceedings in 1723 deprived of the spiritual dignities and banished for life.

Proceedings against Atterbury


Devoted High Churchman as he was, succession of George I of Hanover to the British throne in 1714 seemed to Atterbury prejudicious to the true interest of church. In the spring of 1716, he first responded to approaches from the Jacobites. Convinced that nothing could be attained without an armed invasion by a foreign power, he always counselled caution when he took part in discussions with the Jacobite agent George Kelly in the aftermath of the burst of South Sea Bubble. While in November 1721 he agreed to proposals by Jacobite agents of an armed landing in England, in several months he was frustrated with incompetent fellow conspirators and entirely broke off from them, possibly affected by the illness and death of his wife in April 1722. However, Sir Robert Walpole got wind of the plot and Atterbury was betrayed by the Earl of Mar, the Pretender's secretary of state. While Mar's evidence had to be kept secret, intercepted letters in cipher written by George Kelly, Mar's agent, were used against Atterbury. Atterbury was arrested in August 1722 and committed to the Tower of London. (Oxford DNB)

Report of the Committee of the House of Commons

In January 1723, a committee of the House of Commons was set up to investigate the case, which essentially traced the work of Walpole and his colleagues in the preceding months to collect incriminating evidence against the Bishop. A report of the committee came out on 1 March 1723. (Oxford DNB)

Three Letters of 20 April 1720

The main evidence used against Atterbury was three letters (D.10, D.11, D.12 on p.247 ff.) partly in cipher dated 20 April 1722 (hereinafter, designations such as "D.10", "C.51", "F.11" etc. refer to the Appendix of the Report of the Committee of the House of Commons):

D.10: T. Jones to Chivers [General Dillon (Wikipedia)] (24 words (or parts thereof) were in cipher out of some 330 words; in the postscript, 45 out of some 110 words were in cipher (Davys p.37))

D.11: T. Illington to Musgrave [Earl of Mar (Wikipedia)] (69 out of some 250 words were in cipher)

D.12: 1378 to Jackson [the Pretender] (114 out of some 430 words were in cipher)

While these were written in George Kelly's hand, the code names "Jones", "Illington", and "1378" were all considered to refer to Atterbury, who dictated the letter.

The beginning of the letter to Musgrave is as follows.

I received from Mr Hatfield [George Kelly] (after a long intermission of such favours) a Letter which was very welcome to me. I have also consider'd carefully what he had to offer to me in particular, & intirely agree wth what is proposed, but 978 [my] present bad Circumstances (of which he has already informed you) will 1052 [not] suffer 961 [me] 1616 [to] 122 [be] 30ve [active] 1541 [soon] 1192 [or] 442 [even] to set forward 1602 [the] 2201's [affairs] intrusted 1765 [with] 960 [me] in so speedy a manner as 719 [I] could wish. The best is that as 718 [I] cannot 30 [act] 1145 [openly], ....
(Atterbury to Earl of Mar, 20 April 1722)

A supplement (F.11 on p.303 of Report), in George Kelly's handwriting, to this cipher was found among the papers of Dennis Kelly. (Report, p.124; State Trials p.362) That this supplement, found in July, agreed with the key obtained through deciphering was considered to support the truth of the deciphering. (State Trials p.386)

The supplement cipher (F.11) contains fictitious names for twenty-three names ("Edmuns" and "Eagle" for Mr. Pendernis; "Gainer" and "Gifford" for General Trelawney; "Henderson" and "Hamden" for Sir William Courtney; etc.). It also includes numerical codes as follows. (Entries in bold are not in the supplement but taken from the specimen above to show the consistency of the deciphered code numbers agree with the supplement.)

30 act
75 arrangement
76 addition
77 apprise
78 alternative
79 adverse
80 advantage
81 adjust
122 be
155 boat
156 bay
272 Crawford Mr.1)
273 Cambray
274 congress
275 calculate
276 Carabines
370 disappoint
371 duplicate
442 even
456 encourage
457 enable
458 expence
459 exchange
460 employ
539 facility
540 Field-officer
541 final
593 Gentlemen
718, 719 I
767 Island
806 Kennedy Frank2)
888, 889 Law John3)
890, 891 Law William4)
892 Lowlands
960, 961 me
978 my
1011 Messenger
1012 Major
1013 maintain
1014 mount
1052 not
1086 notion
1145 openly
1192 or
1193 O Brien John5)

1321 possess
1322 pistols
1432 reimburse
1433 repay
1541 soon
1570 Sutton Sir Robert6)
1571 Stanhope Col.7)
1572 Schaub Mr.8)
1573 season
1574 suspicion
1575 slings
1602 the
1616 to
1655 themselves
1656 towards
1717 unite
1718 unfavourable
1719 us
1765 with
1804 we
2201 affair

1) cf. A.7, A.9, A.31, F.1
2) Francis Kennedy, a courtier in the Jacobite court
3) John Law (Wikipedia)
4) William Law (Wikipedia)
5) John O'Brien (?Wikipedia)
6) Sir Robert Sutton (Wikipedia, ambassador in France 1720-1721)
7) Colonel Stanhope (Wikipedia)
8) Luke Schaub (French Wikipedia, ambassador in France succeeding Sutton)

Bills of Pains and Penalties

The House of Commons considered the Report on 8 March and passed a resolution that there was a "detestable and horrible conspiracy". However, at Walpole's insistence, the Commons resolved to proceed against John Plunket, George Kelly, and Atterbury with bills of pains and penalties, rather than by trial and execution. (Oxford DNB, Wikipedia s.v. Atterbury, State Trials p.382)

A bill of pains and penalties inflicts a punishment, less than death, upon a person supposed to be guilty of high offences such as treason and felony, without any conviction in the ordinary course of judicial proceedings, being different from a bill of attainder in that the punishment inflicted by the latter is death (Legal Dictionary). Although the defending counsel argued that bills of pains and penalties and bills of attainder were inconsistent with the constitution and the only few instances were later condemned, the counsel for the bill pointed out that some of the regicides were punished by bills of pains and penalties (State Trials p.443).

Report of the Committee of the House of Lords

Receiving the Report of the Commons as well as related letters and papers, the House of Lords set up a committee on 16 March, who made their Report on 23 April. The Committee confirmed the deciphering contained in the Report of the Commons.

The Lords Committees observing that some Paragraphs of the Letters referr'd to them were writ originally in Cypher, thought it proper to call the Decypherers before them, in order to their being satisfied of the Truth of the Decyphering. The Account they receiv'd from those Persons, was, that they have long been versed in this Science and are ready to produce Witnesses of undoubted Reputation, who have framed Letters in Cypher, on purpose to put them to a Trial, and have constantly found their decyphering to agree with the Original Keys which had been concealed from them. [NB. This passage is similar to that found on Davys, p.53.] It was likewise confirmed to the Committee, that Letters decyphered by one or other of them in England, had exactly agreed with the decyphering of the same Letters performed by Persons in foreign Parts, with whom they could have no Communication; and that in some Instances after they had decyphered Letters for the Government, the Keys of those Cyphers had been seized, and upon comparing them, had agreed exactly with their decyphering. [NB. This part is similar to the Commons Report, cf. State Trials, p.338]
With respect to the intercepted Letters in question, they alledged that in the Cypher used by George Kelly, they find the Words ranged in an alphabetical Order, answering the progressive Order of the Figures by which they are expressed, so that the farther the initial Letter of any Word is removed from the Letter A, the higher the Number is, by which such Word is denoted: that the same Word will be found to be constantly denoted by one and the same Figure, except in the Case of Particles or Words of very frequent Use, which have two or three Figures assign'd to them, but those always following one the other in a progressive Order. They likewise set forth, that in the Cypher above-mention'd, a certain Order is constantly observed as to the placing of the Words made use of, that under each Letter of the Alphabet the first Cyphers are allotted to the proper Names of Places, the next to the proper Names or Titles of Persons, the next to whole Words in common Use, and the last to denote single Letters.
As to the Truth of the Decyphering they alledged that several Letters written in this Cypher had been decyphered by them separately, one being many Miles distant in the Country, and the other in Town, and yet their Decyphering agreed; that Facts unknown to them and the Government at the time of their Decyphering had been verified in every Circumstance by subsequent Discoveries, as particularly that of H--'s Ship coming in Ballast to fetch O-- to England, which had been so decyphered by them two Months before the Government had the least notice of Halstead's having left England: That a Supplement [F.11] to this Cypher having been found among Dennis Kelly's Papers the latter end of July, agreed with the Key they had formed of that Cypher the April before: That the decyphering of the Letters signed Jones, Illington, and 1378, being afterwards applied by them to others written in the same Cypher, did immediately make pertinent Sense, and such as had an evident Connexion and Coherence with the Parts of those Letters that were out of Cypher, tho the Words in Cypher were repeated in different Paragraphs and differently combined. And they insist that these several Particulars duly weighed amount to a Demonstration of the Truth of their decyphering.
As to the other Cyphers made use of by Jernegan, Stanley, and Walter Grahame, they consist only of twenty four Figures, for the twenty four Letters of the Alphabet, and some other Figures for proper Names or whole Words, in the placing of which Names a certain Order is also observed.
These several Particulars they declared themselves ready to attest upon Oath, and to produce sufficient Witnesses to their Character and Integrity as well as their Skill.
(State Trials p.385-386)

The Lords accepted the Report on 24 April (State Trials p.390).

Proceedings against Conspirators

In the meantime, the Commons successively passed bills of pains and penalties against John Plunket, George Kelly, and Atterbury and delivered them to the Lords. After passing the bills against Plunket (State Trials p.390; Lords Journal, 29 April) and Kelly (State Trials p.397; Lord Journal, 3 May), the second reading of the bill against Atterbury was held on 6 May in the Lords.

Disclosure about Deciphering

During the proceedings, there were some discussions about disclosure of the deciphering activities.

On 6 May, when Edward Willes admitted that he did use a key in deciphering letters offered in evidence by the counsel for the bill, Atterbury and his counsel insisted that Willes should produce the key, the request was rejected. (Lords Journal, 6 May) On 7 May, when one Peter Thouvois attested that the copies of the three letters of 20 April 1722 were true copies, except such words as were written over figures, Atterbury asked if he had any express warrant under the hand of one of the principal secretaries of state for opening the said letter, it was resolved "That it is the Opinion of this House, That it is inconsistent with the public Safety, as well as unnecessary for the Prisoner's Defence, to suffer any further Inquiry to be made, upon this Occasion, into the Warrants which have been granted by the Secretaries of State, for the stopping and opening Letters which should come or go by the Post, or into the Methods that have been taken by the proper Officers at the Post-office in Obedience to such Warrants."

Edward Willes was then examined and testified upon oath to the truth of deciphering of the three letters dated 20 April 1722. (Two decipherers were involved in deciphering these letters. On 1 May, the other decipherer Anthony Corbiere testified in proceedings against George Kelly (Lords Journal).)

When Atterbury asked "Whether it is possible to declare certainly, that any Number stands for a Name beginning with any particular Letter, unless the immediate preceding and immediate subsequent Number appears to denote a Name, or Words, beginning with the same Letter", Willes expressed unwillingness to answer, declaring "That it would tend to the Discovery of his Art, and to instruct ill-designing Men to contrive more difficult Cyphers." The Lords resolved to drop the question. When Atterbury persisted on putting several questions to Willes relating to the method of deciphering, the Lords resolved "That it is the Opinion of this House, that it is not consistent with the public Safety, to ask the Decypherers any Questions, which may tend to discover the Art or Mystery of Decyphering."

(The above question of Atterbury may be a strategy formed with the advice of John Davys. Davys thought blanks in the deciphered letters published in the Commons Report provided a basis for objection. It was considered that the decipherer might be in some distress if he were urged to explain how he could be assured of the initial letters of two or three unknown words and yet be wholly in the dark as to the initial letters of several others (Davys p.38-39).)

Truth of Deciphering

Willes attested that the cipher in George Kelly's hand (F.11) was part of the cipher in which the letters of 20 April 1722 were written. (Lords Journal, 8 May)

Atterbury desired of the House that he might have copies of the three deciphered letters in order to see if they were truly decyphered. For once, his request was granted and it was ordered that Atterbury have copies of the three deciphered letters, with the deciphering interlined, to be delivered to him forthwith; and that the said copies be made by one of the clerks of this house, in the presence of the solicitor for the bill, and under the inspection of one of the decipherers.

On 9 May, strenuous defense of Atterbury was made by his counsel, which Lords Journal simply records "Sir Constantine Phipps and Mr. Wynne were heard, in Behalf of the Bishop of Rochester" but which are reproduced in State Trials (pp.398-406 and pp.406-429).

Phipps questioned the deciphering as follows (State Trials p.401).

The next thing I would observe, as to those Letters, is from the Report, Page 42, where the Committee are pleas'd to observe that the Letter to Chivers is, great Part of it, out of Cypher; which seems to allow that the other Part was in Cypher. Therefore it was very necessary, I think, to have printed the Letters in the Cyphers and Characters, in which they were written; and also as they are decypher'd. Then the Persons accus'd would have had an Opportunity of employing Men skill'd that way, to see if they were rightly decypher'd. This was done in Coleman's Case.
The French Papers, in the Appendix, are printed first in that Language, and then as they are translated; which was not so necessary as Printing the Letters in Cypher in this Case: Because almost every one understands French enough to tell, at first Sight, whether a French Letter be rightly translated; but 'tis impossible for a Man of the greatest Skill in the Art of decyphering, to tell, upon a sudden at the Bar, whether a Letter be rightly decypher'd: So that all a Man hath in the World, is to depend upon the Skill and Integrity of the Decypherers. Nor are they infallible; for the Witnesses who decypher'd the Letters admit that there are some Words in them which they could not decypher; and those Words may give a Turn to the whole Sense of the Letters. Nay, Mr. Willes said, that one of the Numbers he could not decypher stood for two Words (cf. notes on Davys p.38-39): He was likewise pleas'd to fay it was impossible that the Number he could not decypher could make an Alteration in the Sense; which is very extraordinary for a Man to swear: But if one Word could not make an Alteration in the Sense, surely two might.

After all, Atterbury's counsel dropped the issue of truth of deciphering, saying on 11 May "That they should not trouble their Lordships touching the Decyphering the Three Letters of the 20th of April, 1722, whereof they had had Copies." (Lords Journal) Later, Atterbury complained of their "allowing me Copies of the Decypher'd Letters, tho petition'd for, till the Trial was so far advanced, and I so employed and weakned by it, that I had not sufficient time to consider them (State Trials, p.435).

Revealing the Pseudonyms

Even after the issue of deciphering was dropped, identity of the persons represented by pseudonyms (fictitious names, feigned names) was another matter. Atterbury's counsel strenuously denied that Jones, Illington, and 1387 referred to Atterbury.

First, identification of the recipients are explained as follows in the Report.

That Chivers, to whom this Letter was directed, means General Dillon, is evident from the following Circumstances.
On the 13th of May, Cane writing to Kelly [E.38], owns the Receipt of these Letters from the Bishop, but over-against the Name of Cane in Plunket's Cypher [C.51], is writ Dillon, and Kelly [E.41.2] answering this very Letter of Cane's, directs to Chivers. Besides, which it appears from innumerable Passages, that Cane and Chivers mean the same with Digby and Dixwell, which have been shewn at large to denote General Dillon.
(State Trials, p.361)

That Musgrave (to whom this Letter was directed) means Marr, is thus proved.
Dillon's Secretary [E.30] writes to Kelly that Mr. Lane (over against which Name in M Plunket's Cypher [C.51] is writ Lord Marr) was much pleased with his first Letter, which, as has been observed before, was writ on the 16th of April.
Soon after a Person [E.32] writes to Kelly, acknowledging the Receipt of this Letter of the 16th of April, and expressing his Satisfaction at Illington's Willingness to be reconciled with Hacket; his Letter is sign'd 918, which Number is found by the Decypherers to denote the proper Name of a Person beginning with the Letter M, and Kelly [E.42] answering this Letter directs to Musgrave.
Besides which, Musgrave is found to be a Person, whose Pension is said to be stopt in England at the very time that a [E.71] Pension granted to late Lord Marr was stopt, and is spoken of in other Letters [E.37, E.41] as one suspected of betraying them, with such Circumstances as fix the Person meant to be the late Lord Marr.
(State Trials, p.361-362)

That Jackson (to whom this Letter is directed) means the Pretender, appears from Plunket's Cypher [C.51], in which, over-against the Name of Jackson, is writ, The King; tho two Names had gone before in that Cypher, over-against which is writ, King George.
Besides which, Plunket's Letter [C.41] mentioning his and Layer's Journey to Rome, is directed to Mr. Jackson; and Jackson appears from other Letters to be the same with Malcom, to whom Application is made in a Letter [I.9] from Edinburgh for a Patent for Knight Baronet, and for Orders to raise one or two Battalions.
(State Trials, p.362)

More controversial than these was the attribution of the pseudonyms Jones, Illington, and 1378 to Atterbury. According to the Report, deciphering indicates the code 1378 represents a name of a person beginning with R (i.e., Rochester). Further, their content indicated that the three letters were written (or dictated) by the same person. Further, the situations mentioned in the letters match those of Atterbury at the time. That is, the writer speaks himself of being in ill health, in great pain, under some sad and melancholy circumstances, which made him uncapable of doing anything regularly at that time, but which he expected would soon blow over, while Atterbury's wife was ill and died six days after and he himself was afflicted with gout.

Further, the three letters were written in George Kelly's handwriting and there was a testimony that Kelly said he was employed in writing letters for Atterbury to the Pretender's agents abroad; that Atterbury never let him carry a bit of his handwriting out of the room; and that Kelly use both a numerical cipher and a cipher of fictitious names.

From such evidence, the Report concluded that the letters were dictated by Atterbury to Kelly and "Jones", "Illington", and "1378" all referred to Atterbury. (State Trials, p.361-362).

Despite the defending counsel's counterarguments, the bill of pains and penalties for Atterbury was passed on 15 May 1723.

Use of the Cipher in Other Channels

The above cipher, used in the three letters said to be dictated by Atterbury, was also used in letters from Spain to Dumville (whose identity was not revealed) and an enclosure considered to be from the Duke of Ormonde to some person abroad whose name begins with L. These were about a planned expedition of the Duke of Ormonde (residing in Spain) to land in England with arms. (State Trials, p.338-340)

The same cipher is also used in letters from George Kelly and to Dennis Kelly.

Other Ciphers Printed in the Report of the House of Commons

The Report of the House of Commons printed relevant documents in the Appendix under sections A-K:

A Foreign Correspondence (p.146)

AA Papers relating to Captain Halstead (p.163)

B Papers relating to Christopher Layer (p.172)

BB Papers relating to an intended Invasion (p.214)

C Papers relating to John Plunket (p.218)

D Papers relating to the Bishop of Rochester (p.244)

E Papers relating to George Kelly (p.261)

F Papers relating to Dennis Kelly (p.299)

G Papers relating to John Sample (p.311)

H Papers relating to the Duke of Norfolk and others (p.319)

I Papers relating to Scotland (p.335)

K Papers relating to Ireland (p.347)

These papers include some cipher materials.

B.Y.1 (p.188)

Section 21 under B, including No. 1 to No. 42, is a larger bundle of papers belonging to Christopher Layer, another conspirator. The first of this bundle, B.Y. 1, is a list of code names for over 300 names and common words:

Ashburnham Ld.Austin
Arran E.James
Argyle D.Alexander
Athol D.Alester
AmsterdamAbigail's House

A cipher table is attached:
a b c d e f g h i k l m n o p q r s t u w x y [z]
o p q r s t u w x y z a b c d e f g h i k l m [n]

B.Y.10 (p.191)

This is a short list of code names. Layer said he received these names from Plunket (State Trials, p.350).


Italics, by the present author, indicates which is the fictitious name.

An expression "Burford's Club" is often used in Plunket's letter to Dillon (State Trials, p.350). Names Digby and Rogers are often mentioned (State Trials, p.353 etc.).

C.50 "The Duke of Berwick's Key" (p.229)

This is a list of code names for 24 people. It is called the Duke of Bewrick's Key in a letter signed "N. Wogan" (State Trials, p.353).

K. JamesMr. Kerry
D. BerwickMt. Dumont
K. GeorgeMr. Atkins
The PrinceMr. Aldsworth
D. MarlboroughMr. Eyrs
Lord SunderlandMr. Dunbar
Lord StanhopeMr. French
Mr. DillonMr. Drycot
Mr. PlunketMr. Reyley
Mr. WoganMr. Henley
The ParliamentMr. Hall
The RegentMr. Ferrard
The CongressThe Company
The Regency of EnglandMr. Fellows

While a letter of the Duke of Berwick to Plunket, dated 6 April 1714, writes "I have received Yesterday your's with a Cypher," the above cipher is different from this in view of the entries "K. George" and "The Regent."

George I succeeded to the British throne in August 1714 and the Duke of Marlborough died in June 1722. France was under Regency from 1715 to 1723. Regency in England was discussed in relation to the King's occasional absence in Hanover.

C.51 "Plunket's cipher" (p.229)

This is a list, in Plunket's handwriting, of code names for more than 100 people and common words.

This cipher was used in a letter from Rogers [Plunket] to Digby [Dillon] dated 23 July 1722 (C.62) and several others (State Trials, p.350). This cipher was employed to identify the addressees Chevers and Jackson (see above) and pseudonyms used in other letters (State Trials, p.352, 353, 363, 444, etc.). The defending counsel questioned the applicability of Plunket's cipher in letters written by Kelly, purportedly dictated by Atterbury (State Trials, p.437), which was countered by an argument that the cipher was used in Kelly's correspondence (State Trials, p.444).

This is a list of code names for about 200 names and words, including verbs . Names beginning with A are always represented by pseudonyms beginning with B and vice versa (This nature is used in State Trials, p.338).

Abbe DuboisBatts
Argyle, D.Brown
AlberanyMrs. Betty
Bavaria, D.Austed
Berwick, D.Ash
Bing, Sir Geo.Asburn
BothmerAndiron, Altop
BremenArtown, Argell
to EmbarkFral
to InvadeKnow, Kiss
Mar, LordLane, Layburne

The Commons Committee made the following observations about this cipher (State Trials, p.353).

There is one farther Particular relating to this Cypher, which the Committee think it proper to remark to the House, which is, that Plunket while he was in Custody desired a certain Book might be brought to him from his Lodgings, but the Messenger's Wife, searching the Book before she delivered it, has deposed [C.49] upon Oath, that she found in it this Letter from N. Wogan. And as the Committee are informed, that most of his other Cyphers and Papers were found hid in the Leaves of his Books, they think it probable, that he singled out this Book, in hopes of recovering and destroying the Cypher that serves to explain his Letters; the Contents of which the Committee will now proceed to lay before the House, and to avoid Repetition of Names, where-ever they can, will make use of the real Names found in his Cypher, instead of the fictitious ones, by which they are expressed in his Letters annexed to this Report.

C.52 Plunket's Cipher Numeral (p.231)

F.11 Cipher in George Kelly's Handwriting taken among Dennis Kelly's Papers (p.303)

This is a supplement to the cipher used in the three letters of 20 April 1722 attributed to Atterbury (see above). It includes a list of code names for 23 people and numerical codes: 72 (arrangement), ..., 1804 (we).

H.34 Cipher enclosed to Mr Burton (p.329)

Appendix H includes papers relating to the Duke of Norfolk and others, among which H.34-H.37 are numerical codes for Mr. Burton. According to the Report, the Duke of Norfolk, among others, was concerned in the treasonable correspondence conveyed through the hands of Mrs. Spelman, to whom several letters from abroad were directed by the name of Mr. or Mrs. Burton (State Trials, p.378).

This cipher distinguishes slashed digits from those without a slash. Thus, while 21-24 designate l, k, j, h, the same digits with a slash designate o, p, q, r.

H.35 Cipher directed to Mr Burton (p.330)

This cipher is designed for French, in view of lack of "w" in the cipher alphabet and the vocabulary of the codes. It distinguishes slashed digits from those without a slash. Thus, while 31-35 designate ba, be, bi, bo, bu, the same digits with a slash designate ca, ce, ci, co, cu.

This cipher was marked D, O, and J and was probably between George Jernegan, a Jacobite, and the Duke of Ormonde (State Trials, p.378).

After this, for each letter of the alphabet, several words are listed with numbers: for A, 1 (Accommodement), 2 (Anglois), ..., 13 (Assemblee); for U, 1 (Vaisseau), 2 (Venise), 3 (Vienne), 4 (Vicomte de), 5 (Viceroy), 6 (Victoire), 7 (Union), 9 (Voyage).

H.36 Cipher directed to Mr Burton (p.330)

This cipher includes substantially the same cipher alphabet as the above image for H.35, with some corrections and omissions. Further, code numbers and nulls as shown below are attached.

H.37 Cipher directed to Mr Burton (p.330)

This cipher was marked "A Key and Cipher, with Mr. Farmer and Jery" and was probably a cipher between the Pretender and Jernegan (State Trials, p.378).

This is a list similar to the one attached to the cipher of H.35 but in English vocabulary. For each letter of the alphabet, several words are listed with numbers: for A, 1 (Army), 2 (Alliance), ..., 7 (Assemblee); for B, 1 (King of England), 2 (of France), 3 (of Spain), etc. Unlike H.35, the arrangement disregard of the initial letters provides a better security (supposing the list is meant to be a code with combinations such as "A1", "A2", etc.).


Reports from Committees of the House of Commons, Vol. 1 (1803) (Google, another scan at Google)

A Complete Collection of State Trials, Vol. 6 (1730) (Google), another edition: Vol. 16 (1816) (Google)

The Historical Register: containing an impartial relation of all transactions ..., Vol. 9 (Google)

Lords Journal (British History Online)

'Atterbury, Francis' in Oxford DNB

John Davys, An Essay on the Art of Decyphering (1737)

Cambridge University Library (2010), 'The Atterbury Plot' in Under Covers: Documenting Spies (online)... Reproduces an image of a letter in cipher.

©2012 S.Tomokiyo
First posted on 22 December 2012. Last modified on 22 December 2012.
Articles on Historical Cryptography
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