A train passenger was stabbed 18 times in front of his 14-year-old son after a heated row over blocking the aisle, a court has heard.

Lee Pomeroy, 51, was attacked by 36-year-old Darren Pencille five minutes after boarding a London-bound train at Guildford, Surrey, in January, the Old Bailey was told.

Afterwards, Pencille’s girlfriend, Chelsea Mitchell, 27, allegedly picked him up and bought hair clippers and razors for him to change his appearance.

Pencille, of no fixed address, denies murder and Mitchell, of Farnham, Surrey, pleads not guilty to assisting an offender.

Opening their trial, Jake Hallam QC said Pomeroy was killed the day before he was due to celebrate his 52nd birthday.

At 1.01pm on Friday 4 January, Pomeroy and his son boarded a train at London Road station in Guildford bound for London Waterloo.

Hallam told the jury: “He did not leave it alive. Within five minutes of boarding that train, Lee Pomeroy had been stabbed in the neck by the first defendant, Darren Pencille. It was the first of 18 knife wounds that he inflicted upon him.

“A little over an hour after he boarded the train, and despite the best efforts of the emergency services who rushed to save his life, Lee Pomeroy was dead.”

The prosecutor told jurors the events surrounding the killing were captured on CCTV and witnessed by other passengers.

The Pomeroys had got into the same carriage as Pencille and made their way down the aisle, the court heard. Hallam suggested the father and son may have been “blocking” Pencille’s way, prompting the snide response: “Ignorance is bliss.”

Pencille allegedly made the comment twice, prompting Pomeroy to ask what he meant. It led to a row which quickly became “heated”, Hallam said. He described the row, part of which was recorded on a mobile phone, as “fast-moving, unexpected and tragic”. Seconds later, Pomeroy was stabbed in the neck, the court heard.

The trial continues.