A DECODED DIARY REVEALS A WAR TIME STORY
P.J. ASTON
157
Abstract
A diary written using a numerical code in a prisoner of war camp in 1941/2 should not be too difficult to decode, should it?
Hong Kong, 1941. On December 8 1941, the Japanese attacked Hong Kong. Seventeen days later, on Christmas day, the brave but outnumbered defending forces surrendered and were put into prisoner of war camps in which many died. A young squadron leader in the RAF, Donald Hill, kept a diary of events during the battle for Hong Kong and for a while during his captivity. In order to keep it secret, he wrote it in a numerical code which, according to the cover of the book in which he wrote, was supposedly "Russel's Mathematical Tables". Donald survived the camp and brought the diary out with him. However, his experiences were so traumatic that he did not like to talk about them. The diary was never translated before his death in 1985.
Guildford, 1996. The phone rings again. The secretary in the Department of Mathematical and Computing Sciences, University of Surrey answers it, polite as always. The caller, Col Ian Quayle of the Soldiers, Sailors and Airmen's Families Association, asks to speak to a mathematician. Having just finished some photocopying, I happen to be the nearest person to the phone so the secretary asks if I will deal with the call. Col Quayle explains about Donald Hill's diary. Mrs Pamela Hill, Donald's widow, is keen to have the diary decoded so that she can find out more about a closed chapter in his life. I suggest that he sends a copy of the diary and say that I will have a look at it.
The Diary. The first page described how the 'Tables' could be used for multiplication. Instructions for multiplying 83 by 26 were given which could be followed on the first page of numbers. However, the claimed answer of 2118 was clearly incorrect. This presumably was part of the disguise.
Twelve pages filled with numbers followed. On each page there