A man accused of murdering another train passenger rang his ex-girlfriend hours after the attack and told her he had “done something bad”, a court heard.

Lee Pomeroy, 51, was stabbed by 36-year-old Darren Pencille five minutes after boarding a London-bound train at Guildford, Surrey, on January 4 with his 14-year-old son, the Old Bailey heard.

Jurors were previously told how it is claimed a row which erupted between the IT consultant and Pencille was over the blocking of an aisle.

Pencille’s former partner and mother of his child, Sarah Fry, who gave evidence by video link, told the jury he rang her at around 9.30pm and said: “I have done something bad today, you’ll see it in the news”.

The defendant later her sent her a text at around 1am the following morning apologising and saying he loved them both, Fry said.

The court also heard from Ingrid Robertson, the defendant’s mother, who when questioned by Justin Rouse QC representing Pencille, said that when her son was in his 20s, she was told he was paranoid schizophrenic.

She revealed her son had been admitted to hospital on a few occasions, had a “fear of crowds”, and struggled on public transport – sometimes ringing her in a panic saying he “needed to get off quickly”.

“He always thought people were looking at him or wanted to do something to him,” Robertson told the Old Bailey.

Witness Kayleigh Carter, who also gave evidence during the trial on Thursday, was asked by Rouse whether Pomeroy had been picking on his client.

Seated behind a screen as she recalled the incident, she said: “I wouldn’t say picking on him, but he was taunting him.”

Describing what unfolded, Carter told Jacob Hallam QC, prosecuting, that she remembers one of the men saying “all I did was be in the way”, which she thought was petty.

She told the jury the two men were talking at first, but not very loudly and directly to each other, adding: “It seemed like they had a tiff.”

Carter said Pencille was angry, but that she did not sense the same emotions from Pomeroy, stating he was more “stern, stubborn and patronising”.

Hearing Pomeroy say “I have never dealt with someone with special needs before”, Carter said that was the first thing she heard that was “really fuelling the anger”.

She said Pencille then said “I am hearing voices right now”, which panicked her.

Carter said Pencille picked up a phone and that she clearly heard him say “I am going to kill this man”, adding that she did not think the call was real as it went through quite quickly.

She said that both of the men were saying they were going to fight at the next station, with the pair eventually becoming “really up and personal”, adding that “neither of them were backing down”.

Hearing Pencille call Pomeroy a racist, she said he responded by saying that if anyone was a racist it was him.

Carter said she saw Pencille strike Pomeroy first, telling the court: “I saw blood straight away, I panicked after that because I had to run through it.”

Heading into another carriage and past the two men, she said blood ended up on her bag.

The court has previously heard how Pomeroy, who was due to turn 52 the day after the “quick and frenzied attack”, was stabbed 18 times in 25 seconds.

Forensic pathologist Dr Olaf Biedrzycki told the jury that Pomeroy had a number of knife injuries including a 10cm deep stab wound, as well as defensive cuts to his hands and arms.

He said Pomeroy had a 6cm deep wound to the left side of his neck, with the knife having cut his jugular vein and carotid artery.

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.

The jury heard how data from their mobile phones showed Mitchell’s device was being used to search for news of the stabbing, while Pencille’s was used to look for hotels in Sussex and near Gatwick.

The trial continues.