The Code Book: The Secret History of Codes and Code-breaking. Simon Singh

but this would have meant crossing territory loyal to her half-brother, and so instead she headed south to England, where she hoped that her cousin Queen Elizabeth I would provide refuge.

      Mary had made a terrible misjudgement. Elizabeth offered Mary nothing more than another prison. The official reason for her arrest was in connection with the murder of Darnley, but the true reason was that Mary posed a threat to Elizabeth, because English Catholics considered Mary to be the true queen of England. Through her grandmother, Margaret Tudor, the elder sister of Henry VIII, Mary did indeed have a claim to the throne, but Henry’s last surviving offspring, Elizabeth I, would seem to have a prior claim. However, according to Catholics, Elizabeth was illegitimate because she was the daughter of Anne Boleyn, Henry’s second wife after he had divorced Catherine of Aragon in defiance of the Pope. English Catholics did not recognise Henry VIII’s divorce, they did not acknowledge his ensuing marriage to Anne Boleyn, and they certainly did not accept their daughter Elizabeth as Queen. Catholics saw Elizabeth as a bastard usurper.

      Mary was imprisoned in a series of castles and manors. Although Elizabeth thought of her as one of the most dangerous figures in England, many Englishmen admitted that they admired her gracious manner, her obvious intelligence and her great beauty. William Cecil, Elizabeth’s Great Minister, commented on ‘her cunning and sugared entertainment of all men’, and Nicholas White, Cecil’s emissary, made a similar observation: ‘She hath withal an alluring grace, a pretty Scotch accent, and a searching wit, clouded with mildness.’ But, as each year passed, her appearance waned, her health deteriorated and she began to lose hope. Her jailer, Sir Amyas Paulet, a Puritan, was immune to her charms, and treated her with increasing harshness.

      By 1586, after 18 years of imprisonment, she had lost all her privileges. She was confined to Chartley Hall in Staffordshire, and was no longer allowed to take the waters at Buxton, which had previously helped to alleviate her frequent illnesses. On her last visit to Buxton she used a diamond to inscribe a message on a window-pane: ‘Buxton, whose warm waters have made thy name famous, perchance I shall visit thee no more – Farewell.’ It appears that she suspected that she was about to lose what little freedom she had. Mary’s growing sorrow was compounded by the actions of her nineteen-year-old son, King James VI of Scotland. She had always hoped that one day she would escape and return to Scotland to share power with her son, whom she had not seen since he was one year old. However, James felt no such affection for his mother. He had been brought up by Mary’s enemies, who had taught James that his mother had murdered his father in order to marry her lover. James despised her, and feared that if she returned then she might seize his crown. His hatred towards Mary was demonstrated by the fact that he had no qualms in seeking a marriage with Elizabeth I, the woman responsible for his mother’s imprisonment (and who was also thirty years his senior). Elizabeth declined the offer.

      Mary wrote to her son in an attempt to win him over, but her letters never reached the Scottish border. By this stage, Mary was more isolated then ever before: all her outgoing letters were confiscated, and any incoming correspondence was kept by her jailer. Mary’s morale was at its lowest, and it seemed that all hope was lost. It was under these severe and desperate circumstances that, on 6 January 1586, she received an astonishing package of letters.

      The letters were from Mary’s supporters on the Continent, and they had been smuggled into her prison by Gilbert Gifford, a Catholic who had left England in 1577 and trained as a priest at the English College in Rome. Upon returning to England in 1585, apparently keen to serve Mary, he immediately approached the French Embassy in London, where a pile of correspondence had accumulated. The Embassy had known that if they forwarded the letters by the formal route, Mary would never see them. However Gifford claimed that he could smuggle the letters into Chartley Hall, and sure enough he lived up to his word. This delivery was the first of many, and Gifford began a career as a courier, not only passing messages to Mary but also collecting her replies. He had a rather cunning way of sneaking letters into Chartley Hall. He took the messages to a local brewer, who wrapped them in a leather packet, which was then hidden inside a hollow bung used to seal a barrel of beer. The brewer would deliver the barrel to Chartley Hall, whereupon one of Mary’s servants would open the bung and take the contents to the Queen of Scots. The process worked equally well for getting messages out of Chartley Hall.

      Meanwhile, unknown to Mary, a plan to rescue her was being hatched in the taverns of London. At the centre of the plot was Anthony Babington, aged just twenty-four but already well known in the city as a handsome, charming and witty bon viveur. What his many admiring contemporaries failed to appreciate was that Babington deeply resented the establishment, which had persecuted him, his family and his faith. The state’s anti-Catholic policies had reached new heights of horror, with priests being accused of treason, and anybody caught harbouring them punished by the rack, mutilation and disembowelling while still alive. The Catholic mass was officially banned, and families who remained loyal to the Pope were forced to pay crippling taxes. Babington’s animosity was fuelled by the death of Lord Darcy, his great-grandfather, who was beheaded for his involvement in the Pilgrimage of Grace, a Catholic uprising against Henry VIII.

      The conspiracy began one evening in March 1586, when Babington and six confidants gathered in The Plough, an inn outside Temple Bar. As the historian Philip Caraman observed, ‘He drew to himself by the force of his exceptional charm and personality many young Catholic gentlemen of his own standing, gallant, adventurous and daring in defence of the Catholic faith in its day of stress; and ready for any arduous enterprise whatsoever that might advance the common Catholic cause.’ Over the next few months an ambitious plan emerged to free Mary Queen of Scots, assassinate Queen Elizabeth and incite a rebellion supported by an invasion from abroad.

      The conspirators were agreed that the Babington Plot, as it became known, could not proceed without the blessing of Mary, but there was no apparent way to communicate with her. Then, on 6 July 1586, Gifford arrived on Babington’s doorstep. He delivered a letter from Mary, explaining that she had heard about Babington via her supporters in Paris, and looked forward to hearing from him. In reply, Babington compiled a detailed letter in which he outlined his scheme, including a reference to the excommunication of Elizabeth by Pope Pius V in 1570, which he believed legitimised her assassination.

      Myself with ten gentlemen and a hundred of our followers will undertake the delivery of your royal person from the hands of your enemies. For the dispatch of the usurper, from the obedience of whom we are by the excommunication of her made free, there be six noble gentlemen, all my private friends, who for the zeal they bear to the Catholic cause and your Majesty’s service will undertake that tragical execution.

      As before, Gifford used his trick of putting the message in the bung of a beer barrel in order to sneak it past Mary’s guards. This can be considered a form of steganography, because the letter was being hidden. As an extra precaution, Babington enciphered his letter so that even if it was intercepted by Mary’s jailer, it would be indecipherable and the plot would not be uncovered. He used a cipher which was not a simple monoalphabetic substitution, but rather a nomenclator, as shown in Figure 8. It consisted of 23 symbols that were to be substituted for the letters of the alphabet (excluding j, v and w), along with 35 symbols representing words or phrases. In addition, there were four nulls (ff.

. d.) and a symbol

which signified that the next symbol represents a double letter (‘dowbleth’).

      Figure 8 The nomenclator of Mary Queen of Scots, consisting of a cipher alphabet and codewords.

      Gifford was still a youth, even younger than Babington, and yet he conducted his deliveries with confidence and guile. His aliases, such as Mr Colerdin, Pietro and Cornelys, enabled him to travel the country without suspicion, and his contacts within the Catholic community provided him with a series of safe houses between London and Chartley Hall. However, each time Gifford travelled to or from Chartley Hall, he would make a detour. Although Gifford was apparently acting as an agent for Mary, he was actually a double agent. Back in 1585, before his return to England, Gifford had written to Sir Francis Walsingham, Principal