Free The King's Spy (Thomas Hill Trilogy 1) by Andrew Swanston Page B

A.
    Continuing with this strategy, Thomas quickly identified ten letters, which revealed the common words AND, A and THE, and parts of other words. With a little intuition and guesswork, he had found the keyword, ADVANCE, and decrypted the message within an hour. It revealed that Sir John Berkeley, with modest help from Sir Bevil Grenville and Sir Ralph Hopton, had defeated a strong Parliamentary force at BraddockDown in Cornwall, capturing cannon and muskets. Reading the plain text, Thomas wondered why Sir John had troubled to have the message encrypted. The gallant knight clearly wanted the king, his court and all his subjects to know of his valour and the great victory it had brought. No doubt there had been similar messages from the other two gentlemen.
    Thomas moved on to the second paper on the pile. Roughly the same length as the first, this one was also a mixture of letters and spaces. As before, he checked it for hidden signs, found none, wrote out each letter of the alphabet across the top of a blank page, and put under each one the number of times it appeared. When this produced a more even distribution than he expected, Thomas suspected he was facing a more complex cipher. Twenty minutes later, he knew he was right. Two substitutions had been used alternately, and he had to find both, just as he had shown Simon in the inn. After another hour, Thomas had identified fifteen letters, which was enough for him to fill in the gaps and write out both substitution alphabets. The substitutions were random sequences of letters, which made them more difficult to decrypt, but both sender and recipient would have had copies, making them vulnerable to discovery.
    A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
    P L O M K I N J U B H Y V G T C F R X D E Z S W A Q
    L A M Z P Q K S N X B C V J D F H G W I O R Y T EU
    It was an intercepted message, revealing that in March Sir Thomas Fairfax had been concerned about his troops’ morale and had asked for them to be paid without further delay. As the message had failed to reach its intended destination, Thomas assumed that Sir Thomas’s troops had remained unpaid.
    By the end of the first day, Thomas had decrypted seven complete documents. They were all alphabetic ciphers, using mixtures of single and double substitutions, and keywords. His eyes and back ached, his legs were stiff and he needed refreshment. He was about to go off in search of food and drink when there was a loud knock on the door. He opened it to find Tobias Rush outside, silver-topped cane in hand and, as at court, dressed all in black.
    ‘Master Hill, I find you hard at work no doubt. I trust I’m not disturbing you. I merely wondered if I could be of any assistance.’
    Caught off balance, Thomas was less than articulate. ‘Master Rush. Good evening. No, no disturbance. I’ve just finished for the day, and wasabout to take some air and stretch my legs.’
    ‘In that case,’ replied Rush, smiling his thin smile, ‘perhaps I may accompany you. You can tell me how you’re progressing.’ Without waiting for an answer, he turned and strode out into the courtyard. Thomas locked his door and followed. ‘I do admire Pembroke,’ said Rush, as they picked their way through the debris towards the college gate. ‘A lovely building, and attractively small, although I see the officers here have paid scant regard to its care. Alas, it’s the same everywhere. Military mess and careless destruction.’
    ‘Yes,’ agreed Thomas, ‘there is something blinkered about the military mind. It seems able to ignore almost anything other than itself.’
    Rush laughed. ‘Nicely put, Master Hill. Let us pray that this war is soon over, so that the university can resume its former life.’ They left the college and turned north up St Aldate’s. ‘And how does your work progress?’
    ‘It has not been arduous. So far, Abraham has given me quite simple tasks, although I expect them to get harder.’
    ‘Good. On Master