In July 1945, a Georgian house on the edge of a Cambridgeshire village became home to a group of 10 German physicists.
By Nic Rigby
BBC News Online
This group included eminent scientists such as Nobel Prize-winner Werner Heisenberg and Otto Hahn, who had discovered nuclear fission.
Hitler's physicists were behind the Allies in developing nuclear power
The scientists, most of whom were involved in Nazi wartime nuclear research, were to spend the next six months in detention at Farm Hall, Godmanchester.
The building was owned by the government and, unbeknown to its "guests", every part of it was wired up with listening equipment.
The transcripts provide a fascinating insight into Adolf Hitler's nuclear programme, according to Northamptonshire author John Cornwell - whose book Hitler's Scientists is published this month.
Mr Cornwell, who lives in a village near Kettering, told BBC News Online that Farm Hall remains "pretty much the same today" as it was in 1945.
"It is an amazing house because it is so much part of Godmanchester and all of its outbuildings were full of those guys [from British Intelligence] tapping into what was being said," said Mr Cornwell.
Werner Heisenberg (centre) with colleagues in 1927
Professor Marcial Echenique, who bought Farm Hall about 25 years ago, recalls that when he first moved in, he discovered all the bugging equipment under the floorboards.
"We discovered all these wires and we did not have a clue as to why they were there," he told BBC News Online.
He later contacted some of the scientists including Erich Bagge who revisited the farm in the 1980s and recalled that he had sometimes climbed over the wall to meet local girls.
What makes the transcripts of the tape recordings so interesting is that the scientists clearly had no idea they were being recorded.
In fact, about a week after they arrived, one of the number, Kurt Diebner, said to Heisenberg: "I wonder whether there are microphones installed here?"
Heisenberg laughed: "Microphones? Oh no, they're not as cute as all that. I don't think they know the real Gestapo methods; they're a bit old-fashioned in that respect."
So do the tapes reveal if Nazi Germany could have developed a nuclear bomb?
Certainly when the Americans captured the German's nuclear research papers they found that the project was at least three years behind the Allies.
They had not even produced the first stage of the atomic programme, a small crude nuclear reactor - built in the US in 1942.
Mr Cornwell said that the tapes suggest the scientists, and in particular Heisenberg, lagged far behind in their knowledge of the physics of nuclear weaponry.
Farm Hall became home to 10 top German physicists
He said that some authors had argued that Heisenberg and his colleagues knew how to develop a nuclear bomb, but hindered efforts because of their opposition to Hitler.
Mr Cornwell rejects this view, citing the transcript taken of a lecture given by Heisenberg to his fellow scientists at Farm Hall.
In it Heisenberg, who headed Germany's nuclear effort, outlined how he believed the Americans developed the atomic bomb.
In his book, Mr Cornwell quotes modern day physicist Jeremy Bernstein who says the lecture shows: "The fantasy that Heisenberg understood how to make a bomb all along but kept 'the secret' is ... absurd."
AFTER THE WAR
Werner Heisenberg and his colleagues mostly returned to academia after being released from Farm Hall
Heisenberg himself was reinstated as an honoured member of the scientific community
Among other honours he was made a Fellow of the Royal Society in London
Heisenberg died in 1971. He was 70 years old
"It turns out the lecture Heisenberg gave to his fellow physicists was all tripe," said Mr Cornwell, who is director of the Science and Human Dimension Project at Jesus College, Cambridge.
However, Professor Echenique believes the scientists may have hindered efforts to build a nuclear bomb.
"If they had developed a bomb it would have been an absolute disaster for the world - we ought to be thankful that they didn't," he said.
Hitler's Scientists, by John Cornwell (Viking), is published on 25 September.