A man admitted lying to police over a bite mark on the body of his four-year-old adoptive son.

Simon McWilliam said he made up the story to protect his wife, Michelle.

The couple, of Gardner Road, Fishersgate, Southwick, deny cruelty.

McWilliam, in an interview with police, said he had seen his wife playfully biting John Smith on a leg to make the boy release his bite grip on her finger.

He told police he had witnessed the incident when, in fact, he had not.

He told Lewes Crown Court yesterday: "I lied to the police. I wanted to protect my wife from someone suggesting she would have bitten him maliciously. I wanted to support my wife."

The couple, he said, first discussed the bite mark as they stood over John's body at King's College Hospital, London.

The boy died from a brain haemorrhage and had 54 bruises and four bite marks on him.

The McWilliams discussed the cover-up story again later that day at their home, before police arrived to interview them, he said.

McWilliam said the boy was a self-harmer and that a bite mark on the boy's arm was inflicted by John himself. He could not explain the other bite marks or the split web of skin under the boy's top lip.

The Saturday before John's death, McWilliam admitted shutting John in his darkened bedroom for five hours as punishment for sticking fingers or cutlery down his throat and being sick.

John had been ill at breakfast and lunch and was sent to bed at 12.30pm. Blackout curtains were closed.

He was still there when McWilliam returned from shopping between 5pm and 6pm.

During the afternoon, he said, Michelle reported hearing a crashing noise upstairs and told him John had fallen out of bed and on to a radiator.

McWilliam said there were new bruises on John's face but the boy did not appear unwell.

He said: "He was very very bruised that weekend." Later, he added: "You got used to him being bruised all the time."

Social worker David Pamely said he was shocked by the intensity of John's injuries when he visited two days later. The boy told him he had fallen upstairs.

In a police interview, McWilliam said John was sent to his bed that same day at 3.30pm for "being stroppy" but yesterday he insisted the boy had merely been told to play in his room, not go to bed.

McWilliam said he had been "confused" with the days.

The trial continues.