Andrew Swanston - The King's Spy

It was a war, too, which found Thomas Hill, peaceful bookseller of Romsey, alone in an abbey room outside Oxford, having witnessed a brutal battle, having himself resorted to the violence he so hated, and having been thrown into the foulest imaginable gaol, in which he had nearly died. And having seen the body of his old friend mutilated by a vicious traitor. It was a war which affected every man, woman and child in England, and which might yet make brutes of all of them.

On each visit, Simon also brought a cup of water into which he had mixed equal amounts of chamomile, sage and garlic, claiming that this was an ancient cure for all manner of diseases, including Morbus Campestris . Complaining that the brew tasted revolting and would do him no good at all, Thomas dutifully forced it down, and by the morning of the third day was strong enough to accompany Simon around the abbey garden. Dressed once again in a plain brown Franciscan habit and leather sandals, he carried an elm branch as a walking stick. Hooded monks worked away in the garden, carefully tending beds of herbs and flowers. They took no notice of Simon and Thomas.

‘Is this where that noxious brew of yours comes from, Simon?’ asked Thomas as they walked.

‘It is. And, noxious or not, it has got you back on your feet. We friars may seem unworldly but we know a thing or two. Which reminds me, I have found a way to get a letter to your sister. Write it today and it will go tomorrow with a troop of the queen’s guard, who are riding to Exeter. Her majesty will be travelling there to embark for France. The guard are preparing the route for her, so that she will be inconvenienced as little as possible on her journey. One of them will make a short detour to Romsey to deliver the letter. If there’s a reply, he will bring it back to Oxford. But be careful what you say. Confine yourself to telling her about your excellent health and the splendid company you keep. Messages can always be intercepted.’

Intercepted messages, thought Thomas. Yes. ‘Thank you, Simon. If you can provide paper and ink, I’ll write a letter this evening.’ They walked slowly around the garden, which was enclosed by a high wall. The wall was old, its bricks and mortar brown and moss-covered. Near the gate, however, a short section had recently been repaired. It stood out against the rest of the wall, and caught Thomas’s eye. The bricks were new, and had been correctly laid so that the vertical lines of mortar between them did not meet. One row began with a whole brick, the next with a half, so that after two bricks in each row one could make out four vertical patterns. Thomas’s memory stirred.

‘You’d better bring plenty of paper and ink, Simon,’ he said. ‘And please bring the message and my working papers. I may need them.’

As instructed, Thomas confined his letter to Margaret to assurances about his own welfare, and to earnest enquiries about her health and that of the girls. He promised to return home soon. The town, the castle, the message and the abbey would have to wait until he did so. Abraham’s murder he might never tell her about. Having finished his letter, he turned to the message. It had not, unfortunately, magically decrypted itself, and there it lay before him, challenging him to reveal its secrets. Forty-five digits — he guessed fifteen numbers of three digits each — four hundred and fifty-six letters, separated by one hundred and thirty-eight spaces, occupying ten lines on one sheet of paper. And possibly hiding something of grave importance to the outcome of the war.

He looked again at his own text:

O N E E Y E I S B R O W N Y E T T H E O T H E R I S B L U E

and its encryption, using THOMAS as the keyword, as

H U S Q Y W B Z P D O O G F S F T Z X V H T E J B Z P X U W

There were the repetitions of BZP, coinciding with ISB in the plain text, and there was the interval of eighteen letters between the start of the first sequence and the start of the second.

He turned back to the encrypted message. The numbers would have to wait. He would gamble on their being codewords, and therefore outside the encryption of the rest of the text. There were the seven repeated three-letter sequences — RFU, WHT, QFV, RVV, IFS, AAD, WWJ — and one four-letter sequence — WZTD, which he had marked by putting a line under them. The letter distances between all repeating sequences were divisible by five, one and themselves, but by no other number. One letter only would have meant a single shift and could be discounted. But there might be more repetitions. Finding them was laborious work, and he could have missed some. If his theory was right, however, and his simple test suggested that it was, the distances between any unnoticed repetitions would also be divisible by five, and would be repeated in the plain text, albeit with different letters. He was almost certain that the keyword had five letters.

That evening, Simon came to collect the letter to Margaret. As usual, he brought food from the abbey’s kitchen, which they shared, and grim news from Oxford. New taxes were being levied on the townspeople, and the colleges were being forced to supply new regiments to defend the town. Even the college servants were not exempt.

The mention of college servants reminded Thomas of Silas Merkin. He must try to contact Silas. ‘Not actions likely to endear the king and his court to the people.’

‘Indeed not. The queen, too, is despondent. Her mood, as ever, reflects that of the king.’

‘And Jane? Have you seen her?’

‘I have. She is well, and asks after you. An admirer, Thomas, I fancy.’

Thomas felt himself blush. ‘Come now, Simon, I hardly think so. We get on well. Nothing more.’

‘Well, Jane would like to visit you. I’m reluctant to arrange it because she would learn where you are, which might be dangerous for her and for you. She’s probably being watched, and Rush must on no account learn of your whereabouts.’

‘It would cheer me greatly to see her, Simon. Can you not think of a safe way for her to come?’

‘If you wish it, I’ll try. But do not raise your hopes. Rush’s men are everywhere.’

‘And what of dear Abraham, Simon?’

‘The coroner released his body today. He will be buried in two days’ time at the Church of St Barnabas, just outside the west wall. He liked the place. The funeral is set for ten.’

Thomas was silent. He felt guilty for not having grieved properly for his old friend, and now he could not attend his funeral. He would have to mourn in private.

‘Here’s the letter, Simon,’ he said, handing it over. ‘God willing, it will arrive safely, and there will be a reply.’

The next morning, Simon did not visit and Thomas’s breakfast was brought by an elderly monk who could see little and said nothing. When he had eaten, Thomas laid out the encrypted message on the table and studied it again. It was still the same:

URF UBD HE XQB TF KGA OEMD RRFUO TLC WMG LRB WHT R XHGORKZ IO KPW769 WA MQFV BVMF HPL ZFTD RVV57 4SEWMFREJ VGL SVKMGE 852 GTSC WZTD QE TIJG IVL GJT RA KDOE IK EOJAAQLV GGJR MQU IOIGSI GRQF HBFZG JGY ALG EE OLWEEA GJR YIFS1 82AEL2 64SGE SC AAD ZVY JP KP WXR JB JTN XBZ77 5XNW WJBS LA LWAK371 EAIH TPA AD RVV BAP TWPVV AGDN WWJ URR VUT IW EW HTI QCT WY QDT37 1IE852 769UMHT RKC CONT WSGV WMG IEN DJEE KWIHV ZW PNU EAIH371 ZV GJR YIFSS NQ DA BV NGGCVL LD SVMC IRLKW DN KMJ BS WINDU IITAE KW42177 5OX LCIVK IJM LXMV IFS PCI UT FFZ SEPI MZTNJQGCOW3 71E ZDWZTD QE SZGJ GYB LD 574SKIFS RVIV N GFL OX LC QFV WV AZPLCJJX NX IF TNU BG IHZA OP RJWGC

And still it revealed nothing of itself. Having been intercepted nearly two weeks ago, it might, in any case, no longer be useful — a thought he quickly put aside. His job was to decrypt this text, whatever it turned out to be.

Proceeding on the assumption that the keyword consisted of five unrepeated letters, Thomas wrote out each of the letters that would have been encrypted using the first letter of the keyword. Ignoring all numbers and spaces, he began with the first letter, U, followed by the sixth, D, the eleventh, B, and each following fifth letter, until he had listed ninety-two letters. In a text of four hundred and fifty-six letters, the first letter of the keyword would have been used ninety-two times, and the other letters ninety-one times. It was a painstaking task and easy to make a mistake. He worked slowly.