As a boy David Dennis used to cycle regularly from the home of his mother and stepfather to spend weekends with his grandparents. He was, it was said, “the apple of his grandmother’s eye.” When he was 18 he repaid their hospitality by murdering them both.

Grandad John Spriggs, a 70-year-old retired blacksmith, and his 69-year-old wife Florence lived in Scredington, south-east of Sleaford, Lincolnshire, where they ran a small petrol pump at the gable-end of their roadside home, Stone Croft Cottage, and sold cigarettes. That made them a popular couple among the villagers.

But in February 1958, they seemed to vanish into thin air. The petrol pump and the cigarette sales were transferred into the hands of grandson David, now 18, who appeared to be living in the cottage with his girlfriend Kathleen Gillighan, 24.

By MARCH 7th there was so much gossip going on that Sleaford Police decided to investigate. They went to the cottage and found John Spriggs’s dead body slumped in a chair in the dining-room, his chest caved in by heavy blows.

Upstairs in the bathroom his wife had been killed by repeated blows to the head. Earlier that day Dennis and his girlfriend had decamped to a flat in Upper Park Road, Hampstead, north London. There Dennis was arrested and whisked back to Sleaford, where he was charged with double-murder.

He was brought to trial at Lincoln Assizes on June 2nd, where he pleaded not guilty to capital murder in the course of theft. Under the new Homicide Act, if he had murdered his grandparents to rob them he could hang, but if that were not his motive he would escape the gallows.

Kathleen Gillighan, appearing as a witness, said Dennis told her he had been left the cottage by his grandparents. He allowed her to enter only the sitting-room.

Dennis refused to be represented, and defended himself. When he had finished his case the judge told the jury: “This young man who is no more than a boy conducted his defence with the most outstanding ability. One can but admire the performance which he showed before you.”

The jury found Dennis not guilty of capital murder but guilty of murder. He was sentenced to life and released in 1972 after serving 14 years.