Miles William Giffard was born on December 18, 1925, in St Austell, Cornwall, England. He hailed from a prominent family; his father, Charles Giffard, was a respected solicitor and clerk of the court, while his mother, Elizabeth, was active in local Conservative politics. Giffard received his education at prestigious institutions, including Rugby School and Blundell's School. Despite these opportunities, he struggled to find his footing in adulthood.

By his mid-twenties, Giffard had failed to establish a stable career. He attempted to follow in his father's footsteps by training as a solicitor but did not complete his qualifications. Instead, he held various short-term jobs, including selling ice cream, and was often unemployed. His relationship with his parents became increasingly strained, particularly with his father, who viewed him as a disappointment and reduced his financial support. Giffard's mental health was a concern from a young age; he began seeing a psychiatrist at 14, who noted signs of mental deterioration. By 26, he was described by his doctor as an "idle little waster."

In 1952, Giffard began a relationship with 19-year-old Gabrielle Vallance, which his parents disapproved of. They pressured him to end the relationship and focus on finding stable employment. In a letter to Gabrielle, Giffard expressed his despair, writing, "Short of doing him in, I see no future at all," referring to his father.

On November 7, 1952, tensions between Giffard and his parents reached a tragic climax. After his father refused to lend him the family car, Giffard spent the afternoon drinking alone at their home, Carrickowl, perched on the cliffs near St Austell. When his parents returned that evening, Giffard attacked his father in the garage with a lead pipe, killing him. He then entered the house and bludgeoned his mother to death with the same weapon.

In an attempt to conceal the murders, Giffard transported his parents' bodies in a wheelbarrow to the edge of the cliff at the end of their garden and threw them into the sea. He then drove to London to meet Gabrielle, taking her to see a Charlie Chaplin film, as if nothing had happened.

The bodies were discovered the following day on Porthpean Beach, prompting a police investigation. Giffard was quickly identified as a suspect and arrested in London on November 8, 1952. Despite evidence of his mental health issues, including a diagnosis of schizophrenia, the jury at his trial took only 35 minutes to find him guilty of murder. He was sentenced to death and executed by hanging at Horfield Prison in Bristol on February 24, 1953.