A pub landlord killed an old friend with a single punch after they had engaged in "banter" on the way to a wedding reception, a jury was told today.

John Harrington, 51, from Redbourn, struck Terry Hutchinson in the face, knocking him to the tarmac of the West Herts Golf Club, near Watford, where he suffered a traumatic brain injury, it was alleged.

Mr Hutchinson, 64, was treated at the scene and was taken to St Mary's Hospital, where he died three days later.

There was no obvious reason for the assault but the two men had been drinking heavily before they were taken to a wedding reception at the club at 11pm on May 24 last year, Luton Crown Court was told.

Prosecutor Robert O'Sullivan QC said: "Mr Harrington did not intend to kill Terry Hutchinson. He is charged with manslaughter.

“The prosecution say he deliberately and unlawfully assaulted Mr Hutchinson and that assault was a significant cause of his death.”

He said Mr Hutchinson, who suffered a heart condition, had moved to Thailand in 2008, where he had married.

In May last year he was back in the Watford area, visiting family and friends. He had been drinking in the Red Lion in Bushey before being driven at 5pm to the defendant's pub, The Bull in Redbourn.

They drank at the pub before the two men and another friend, who had joined them, were taken to the golf club where members of John Harrington's extended family were attending a wedding reception.

Mr O'Sullivan said: "There was a fair bit of banter on the part of Mr Harrington who was in the front seat and Mr Hutchinson, who was in the backseat.

"What may have started out as drunken high spirits concluded with the defendant assaulting Mr Hutchinson with such force he went to the ground immediately and did not get up."

He told the jury of eight men and four women that Pathologist Dr Nat Carey found that the victim suffered a fracture to his nose consistent with a severe impact such as a full fist blow.

When questioned, Harrington told the police: "I think I slapped him. I don't think I punched him. It was an open hand, not a fist. It was a playful slap."

He said he had drunk 10 pints and four large Bacardis. Mr Hutchinson, who he said was a very good friend, had drunk the same.

In the witness box, the defendant's best friend David Say told the jury that in the car on the way to the reception: "We were having a laugh like we usually do. We were larking about - poking each other."

At the golf club, the other two men were ahead of him and were mucking about. He went on: "They got a bit boisterous so I split them up and told them they were idiots. They were pushing each other around."

He said he did not see what happened when Mr Hutchinson went to the ground, but said he went to his aid.

John Harrington, of High Street in Redbourn, denies manslaughter.

The trial continues.