Gwynne Owen Evans was born on April 1, 1940, in Maryport, Cumberland. His birth name was John Robson Walby. Gwynne was the third child and the eldest surviving son of Thomas and Hannah Walby. He attended a secondary modern school in Maryport. During his school years, he occasionally visited Dovenby Hall Mental Colony in Cockermouth.

At the age of 15, Gwynne left school. His first jobs included working as a page boy at a hotel in Carlisle and as an engine cleaner for British Railways. After a while, he faced periods of unemployment. In 1957, he received a supervision order and was sent to a hostel in Bristol. Later that same year, he joined the Border Regiment but was discharged in March 1958 for being "unfit under existing standards." He enlisted again in the Royal Inniskilling Fusiliers in November 1958 but was discharged in February 1959 for the same reason.

Following his military service, Gwynne began using the name Owen Evans. He found work with British Railways again for a short time. He then tried to join the Royal Air Force, which accepted him in July 1959, but he was discharged after four months for being "physically unfit for Air Force service."

From September 1960, he held several short-term jobs in the area of Workington. While working at Lakeland Laundry, he met a man named Jack West. In October 1961, he moved to Birmingham, where he worked various jobs, including as a kitchen porter, driver, and lift attendant.

On April 5, 1963, Gwynne was convicted by magistrates in Carlisle for theft and fraud. He stole two half crowns from a friend and obtained money and a railway ticket by pretending to have lost his wallet. He received a fine and chose to serve four days in detention. In the following month, he spent three months in prison for driving without a license.

In October 1963, Gwynne enlisted in the Lancastrian Brigade but was discharged in November when his past convictions were discovered. He then moved to Preston, lodging with Peter Allen and his wife. For a short time, he worked for an agricultural trading society.

In January 1964, Gwynne committed his first crime with Peter Allen when they stole lead flashing from an empty house. Later that month, they broke open a cigarette machine and stole items from it, along with a car and a van, using them in several burglaries. After facing a fine for these actions, Gwynne worked briefly for a dairy but was dismissed due to absenteeism.

During this time, he began to speak with a Welsh accent, claiming he had adopted the name Evans after learning that his parents were German. He stated that he was born in Innsbruck.

On April 6, 1964, John West, a 53-year-old van driver, returned to his home in Seaton, Cumberland, after a regular day at work. Later that night, a neighbor heard a noise coming from his house and saw a car leaving the area. The police were called and found West dead in his home. He had suffered severe head injuries and a stab wound to his chest.

The police discovered a raincoat in the house that contained a medallion belonging to Gwynne Owen Evans and an Army Memo Form associated with a woman named Norma O’Brien. The police traced O'Brien, who confirmed that she had met Evans before and recognized the medallion.

Evans and Peter Allen had stolen a car to reach West's house. After the murder, they abandoned the vehicle in a builder's yard, which led to a report from a neighbor about its suspicious presence. The car was traced back to the murder scene. Evans and Allen were quickly located through their previous criminal records.

On April 8, 1964, police arrested Allen at his home. He initially claimed he was not involved but later said Evans had proposed robbing West. Evans, on the other hand, stated that he only intended to borrow money from West and that Allen had forced his way into the house to commit the robbery.

During the investigation, both men shifted blame onto each other. They were charged with murder less than two days after the crime.

Their trial began on June 23, 1964. During the trial, each accused the other of being the primary attacker. Key testimony came from Mrs. Allen, who supported her husband's claim that both men were involved in the murder. After deliberating for three hours, the jury found both men guilty of capital murder.

Both men appealed the conviction, but their appeal was denied. The execution date was set for August 13, 1964. The Home Secretary decided against commuting their sentences, and both men were ultimately executed that morning. Gwynne Owen Evans was hanged at Manchester's Strangeways Prison, while Peter Allen was executed at Walton Prison in Liverpool.