A father accused of killing his terminally ill son described the moment he placed a pillow over his son's face and smothered him.

Taking the stand for the first time at Lewes Crown Court yesterday Andrew Wragg took the jury through the events leading to ten-year-old Jacob's death in July last year.

He said: "I went straight through the front door and turned left into Jacob's bedroom. He was fast asleep.

"I went over to his bed. I took a pillow from the side of him, not from under his head - that would have disturbed him.

"Then I knelt across him and put the pillow over his face."

The defendant, a decorated former SAS soldier, said his son did not struggle or move.

He went on: "Then I laid down with him. He did not make any noises ... it happened straight away when I put the pillow on his face. It was immediate.

"I laid with him. I stroked his head. I had a sense of relief it was all over. And then I was just very, very, very upset. I was crying and I broke down."

He spent 20 minutes talking to his dead son "explaining why I felt it was the best for him", he said.

Jacob was crippled by the degenerative disease Hunter Syndrome, which left him deaf and in a wheelchair. He was not expected to live past his mid-teens.

In the public gallery at Lewes Crown Court yesterday Wragg's father Bob, an ex-policeman, wiped away a tear as his son, almost whispering, told his story.

After killing Jacob, Wragg telephoned his wife Mary, explaining what he had done, he said.

He told the court he wanted to call the police but she stopped him, saying she wanted time with Jacob.

Mrs Wragg sobbed in the public gallery as her ex-husband continued: "I was still in the room when Mary came in.

"She said: 'Oh my God'. I moved back from Jacob so she could spend some time with him, which she did.

"Afterwards, she turned round and hugged me.

"We spent time together with him and then moved to the kitchen where she poured some wine for both of us.

"I toasted Jacob saying, 'He is at peace'."

As Wragg was cross-examined about his wife's involvement in the killing, Mary Wragg stared straight ahead.

She touched the lock of Jacob's hair pinned to her cardigan and put her head down to smell it and stroke it against her face.

Earlier, Wragg testified how his wife had made it very difficult for him to see their children when they had split for three years before.

He said: "She refused to let me. She said because I had left I no longer had the right to see them as and when I wanted."

The court also heard that Wragg served with the Army for almost five years and rose to the position of lance corporal before being discharged on compassionate grounds in 1996.

He was described as a "mature, determined and ambitious soldier" with "exemplary" conduct and was awarded a UN service medal for his work in Bosnia.

A report from a major in July 1996 said: "I have been impressed with the way Lance Corporal Wragg has conducted himself and the way he has kept his family together during this difficult time."

Wragg said on one occasion his badge and beret were removed for failing to sign in and out correctly but two weeks later he was reinstated and promoted.

He denied claims that he had been involved in bullying.

The defendant later spent three "terrifying" months working in Iraq as a private security guard and narrowly escaped death when a suicide bomber struck, the court heard.

When he got back to the UK, he said he spent a night in London with his colleagues drinking as it was not something they were able to do in Iraq.

When he returned he was shocked at the deterioration in Jacob's condition.

He said: "There were massive changes. I don't think he recognised me.

"His head had become more deformed and his face was drooping down one side.

"His hands were more clawed and he was completely on tiptoes.

"I didn't believe he had a future. Any future he did have was going to be painful and undignified."

Pausing, Wragg said the hardest thing for him was not knowing if his son was in pain.

He said: "I thought he was but he couldn't express pain normally. It was getting worse rapidly."

When asked to respond to evidence from former carers that Jacob had laughed and been lively during his final months, Wragg said: "I don't believe he was smiling. I think it was a muscular reaction. It was hard to tell what his brain was doing.

"He couldn't walk more than 30m without falling over. Whenever he left the bungalow he would be in his wheelchair."

Wragg refuted claims by his ex-wife that he favoured younger brother George over Jacob and that he was embarrassed by his disabled son.

He said: "That is completely untrue. That is probably one of the worst things I have heard this week.

"I never ever said he embarrassed me. I was proud of my son.

"I always included Jacob. It is ridiculous to suggest I favoured George."

Wragg said he was was angry about the treatment the family had received from social services, saying that was why he had sometimes been unhelpful when they had visited.

He said: "I became disillusioned with social services and therefore would leave anything to do with them to Mary.

"I was angry and frustrated about the false promises they would make."

Wragg denies murdering Jacob but admits manslaughter on the grounds of diminished responsibility.

The trial continues.