Obituary: Alan Nunn May

Nuclear physicist and spy. Died aged 91.

Alan Nunn May holds an important place in Cold War history as the first person convicted for supplying atomic-bomb secrets to the Soviet Union.

He was jailed in 1946 and served seven years.

But only on his death did he give any substantive account of his espionage activity, in the form of a statement dictated in his final days.

A gifted nuclear physicist at King's College London in 1939, Nunn May was a natural recruit for secret wartime research, first working on radar, then on early studies for the atomic bomb.

He later worked on nuclear reactors in Canada, on the fringe of the Manhattan Project, and used this position to supply reports on nuclear progress to Soviet intelligence and pass on stolen samples of processed uranium.

He was caught when a Soviet cipher clerk defected in Canada and revealed his role.

Coming just months after the end of World War II, the case caused enormous shock and had profound political repercussions.

Not only was it the first public proof that the Soviet Union had spied on its wartime allies and penetrated the security screen around nuclear weapons development, but it also helped to end co-operation between the US and Britain on nuclear matters.

The result of that was the British-made bomb.

Nunn May pleaded guilty at his trial but refused to identify associates or give details of his spying.

He insisted in a brief confession: "The whole affair was extremely painful to me and I only embarked on it because I felt this was a contribution I could make to the safety of mankind."

He revealed nothing more until the release by his family of a text dictated to a step-granddaughter, Alice Evelegh, three weeks before his death.

Entitled "This is a Disclosure of How I Became a Russian Spy", it appears to resolve many of the mysteries of the case while making clear that he went to his grave believing his actions were justified.

Although it was known he was left-wing and pro-Soviet before the war, Nunn May confirms for the first time in this document that he was a Communist Party member.

He says his first act of espionage was in Britain after he had read a secret American report warning (incorrectly) that Nazi Germany might have the ability to explode a "dirty bomb" that would spread radioactive poison over a large area.

"It seemed to me that the possible danger to the Russians from the effects of the dirty bomb was even greater than the possible danger to the West. So I took the measure of contacting the Russian Secret Service."

The effect was to establish him as an asset in the eyes of Soviet intelligence, and when he was sent to Canada in 1943 they instructed him to set up a radio communications station for them there.

Nunn May says he thought this dangerous, and with the Soviet Union by then gaining the upper hand in its struggle with Germany he "did not see the point" and did nothing.

The war was in its final year when a Soviet agent approached him again in Montreal and asked for information on the atomic bomb.

"It seemed to me that they ought to be informed," he says, "so I provided all the information I could."

He reported on the reactor work in Canada and informed on visits he made to a Manhattan Project laboratory in Chicago.

The "disclosure" adds: "Because I had access to the entire library of research documents on nuclear power (a great deal of which was provided by the US), I was able to borrow these documents from the library and hand them over to the agent, who would take them to Ottawa, photocopy them, transmit them to Russia and then return them to me."

Although identified as a spy at the end of 1945, Nunn May was not immediately arrested. MI5 allowed him to return to London in the hope that he would contact and expose other agents.

He never did, and his new account confirms long-held suspicions that he was tipped off, although he does not say by whom.

On his release from prison, he worked for a scientific instruments firm in Cambridge before taking a post at the University of Accra in Ghana in 1961.

He became Professor of Physics and remained in Accra until his retirement in 1978, when he returned to Cambridge.

In 1953, he had married Hilde Broda, an Austrian doctor then practising in Cambridge, who accompanied him to Accra where she continued her medical career.

The family describe them as a close couple and his retirement as a happy one.

- INDEPENDENT