JOHN Herivel, a leading codebreaker at Bletchley Park during the Second World War, has died aged 92.

Mr Herivel, of Oxford, was known for a discovery that led to the breaking of a crucial part of code in 1940.

He was born in Belfast in August 1918 and won a mathematics scholarship to Sidney Sussex College at Cambridge in 1937 before being recruited to Bletchley Park, in Buckinghamshire.

When Mr Herivel arrived at Bletchley Park, aged 21, efforts were already being made to find new ways of cracking German military codes, especially the infamous ‘red’ code.It was in the breaking of this that Mr Herivel made his vital contribution, which became known as ‘The Herivel Tip’ in a process called ‘Herivelismus’.

He had the insight that there must be many German operators of his own age using Enigma code machines under wartime stress.

He correctly assumed that some would take shortcuts through the official procedures to make their life easier.

Mr Herivel’s breakthrough allowed codebreakers to narrow down the possibilities of code, and three months later, to break the Red cipher.

Following the war, Mr Herivel worked as a lecturer in the History and Philosophy of Science at Queen’s University, Belfast. He retired to Oxford in 1978 as a Fellow of All Souls, and published a number of books, including Herivelismus and the German Military Enigma in 2008.

His friend Mr Lipscomb remembered: “Returning from lunch one day we fell to discussing the difference between genius and talent.

“‘A genius’, said John, ‘is someone like Mozart, Newton or Einstein who did remarkable things all their life, but a man of talent may have a stroke of genius once in a lifetime’.

“That man was John. I shall miss him sorely.”

Mr Herivel was married to Elizabeth Maude Jones from 1947 until her death in 2005. He is survived by two daughters.