On 2 November 1952, two teenagers, Derek Bentley and Christopher Craig, tried to break into a warehouse in Croydon, Surrey. The police were called and in the minutes that followed, Craig wounded one policeman and shot another dead.

At 16, Craig was too young to hang, but Bentley, at 19, was not. Even though he had not fired a shot or carried a gun and was under arrest at the time PC Sidney Miles died, Bentley was deemed to be guilty of murder. The law – of joint felonious enterprise – was unjust and Bentley had an IQ of 66 (the national average is 100). Even so, he was hanged at Wandsworth in February 1953.

Nearly forty years later, PC Claude Pain, who was there at the time of the shooting, told a different story. He was on the warehouse rooftop and saw the whole thing. What really hanged Bentley were the words he allegedly used, ‘Let him have it, Chris’. And Pain did not hear those words.

M.J. Trow's Let Him Have It, Chris, published in 1990, was based on Pain’s new evidence. Eight years later, the conviction against Bentley was overturned – not as a result of police corruption, but because of the appallingly partial performance of the trial judge, Lord Goddard.

At the time, access to any material relating to the case was denied and only now, with the Freedom of Information Act, can Pain’s testimony be refuted. He was not on the roof. His original deposition is still in The National Archive.

This book aims to put the record straight. There was indeed a dreadful miscarriage of justice in 1952 – one of many before and since – and, in a way, Claude Pain was part of it.