IT has been often observed that one can be led into error by the simple application of the ethical principles and moral judgments of today to the human behaviour and activities of the past.

Even taking such comment on board, one can still, I believe, readily reach the conclusion that Alan Turing, the mathematician and Cambridge don, was shabbily treated by the generation within which he lived ("Homosexuality conviction pardoned", The Herald, December 24).

His work at the Code and Cypher School at Bletchley Park was monumental. He played a key role in cracking the codes used by the Germans through their Enigma enciphering machines. It is generally acknowledged that his greatest invention was the Colossus, the world's first electronic digital computer, which produced the answer to decoding problems by applying different possible codes until it came up with one which worked.

His contribution to the victory of the Allies in the Second World War and, more generally, to the world of computing was enormous, and justifies him being regarded as one of the leading figures of the 20th century. It is tragic that in 1954 his life was brought to an undeserved end.

Ian W Thomson,

38 Kirkintilloch Road,

Lenzie.