As the hero of the film “The Light That Failed” fired his revolver five times, a sixth shot also rang out on the evening of MAY 30th, 1946, in Bristol’s Odeon cinema.

The audience assumed this was part of the soundtrack. It wasn’t. Robert Jackson, the cinema’s manager, lay dying in his office, a bullet in his temple.

He was found by one of his staff, and he died in hospital the following morning. Meanwhile detectives had ruled out robbery as the murderer’s motive. The cinema’s takings were still in the manager’s safe, the keys in his pocket, and for 46 years the case remained unsolved.

Then a 49-year-old tattooist walked into a Bristol police station and told detectives that the killers had been his father, known as Billy the Fish, and another man, and both were now dead.

His story satisfied the police that he was right, but he could throw no light on the murder’s motive. He was only a toddler at the time, and all he could say was that his father – who had died in 1989, aged 81 – was “a monster without a conscience – he never lost a single night’s sleep over the killing.”