Peter Anthony Allen was born on April 4, 1943, in Wallasey, Cheshire. He was the second son of Richard Thomas Allen. Peter attended a secondary modern school in Wallasey, but he left school when he was 15 years old. He started working right away but struggled to keep jobs. In one month, he obtained two jobs and lost them both for being careless. After that, he worked for three months as a pipe-cleaner.

On July 10, 1958, Peter joined the Junior Leaders Regiment of the Royal Artillery as a junior gunner. He served for 11 months before being discharged on June 13, 1959, because he was "no longer required." Despite his short time in the army, he received a good reference.

After leaving the army, Peter worked for two trucking companies over the next two years. He was dismissed from the second company in October 1961 after he received a promotion. He was said to be unable to handle the responsibility that came with the new position. While he was a lorry driver, he received his first criminal conviction in August 1960 for aiding and abetting the taking of a car. He was given a conditional discharge.

On November 11, 1961, Peter married Mary, who was a cinema usherette. They had a Catholic wedding and moved to Manchester. Soon after, Peter found a job at a scrap dealer but was dismissed in April 1962 for poor timekeeping. He then worked for six months in a dairy and followed that with another six months at a steel works. By April 1963, he had moved to Preston.

In Preston, Peter got a job as a laborer with an agricultural trading society. Unfortunately, he injured his back after two months and was unable to continue working. He was not officially dismissed until January 1964. Later that month, he began committing robbery offenses with a friend named Gwynne Evans. In February 1964, he started working at a dairy but was again dismissed for absenteeism after just one month.

John West, known as Jack, was murdered on April 7, 1964, at his home in Seaton, Cumberland. West, a 53-year-old bachelor and van driver, was found dead from severe head injuries and a stab wound to the chest. His next-door neighbor heard a noise during the night and saw a car leaving the area. The police arrived and discovered West’s body inside his house.

A raincoat was found at the scene, which contained a medallion and an Army Memo Form. The medallion had “G.O. Evans, July, 1961" inscribed on it, linking it to Gwynne Evans. The memo form mentioned a young woman named Norma O'Brien, leading the police to her in Liverpool. O’Brien confirmed knowing Evans and identified the medallion.

Investigators traced a stolen car that Evans and Peter Allen used to reach West's home. The vehicle was located in Ormskirk, Lancashire, after a neighbor reported suspicious behavior. Detectives connected Evans and Allen to the murder by tracing them through their criminal records and family ties. Allen was arrested on April 8, just two days after the murder.

During questioning, Allen initially denied involvement but later changed his story, claiming he was with Evans when they decided to rob West. He said Evans entered West's home first and, when West confronted them, he fought back. Evans, on the other hand, accused Allen of being responsible for the murder when he was taken into custody. Both men were charged shortly after.

Their trial began on June 23, 1964. During the trial, both men blamed each other for the murder. The jury heard a key testimony from Mrs. Allen, who asserted both men were involved in the attack. After deliberation, the jury found both men guilty of murder, leading to their death sentences.

They appealed their sentences, but the appeal was dismissed. They were scheduled to be executed on August 13, 1964. Both men were hanged that morning, making them the last two people executed in Britain.