A mother said she would never have left her terminally ill son alone if she had known her husband was planning to kill the boy.

Mary Wragg told Lewes Crown Court she was expecting an evening alone with husband Andrew when she agreed to leave Jacob, ten, alone and take the couple's youngest son to her mother's house for the night.

While she was out, former soldier Andrew Wragg, 38, smothered Jacob, who was suffering with a rare degenerative disease, with a pillow at the family home in Worthing.

Mr Wragg denies murdering Jacob on July 24 last year but admits manslaughter on the grounds of diminished responsibility.

He claims he took Jacob's life in a "mercy killing" while suffering an abnormality of mind.

Yesterday at court, Mrs Wragg was asked why she had left Jacob alone on the night of the killing even though the defendant had called earlier in the day to say he was going to "take Jacob away and kill him".

Mrs Wragg said she challenged her husband about what he intended to do and only agreed to take six-year-old George to her mother's because she believed Wragg would not kill Jacob.

The court heard how during police interviews after the killing, Mrs Wragg told officers her husband had said he had seen something was wrong in Jacob's eyes.

But Mrs Wragg denied there had been major changes in Jacob's condition in the weeks and months before he died.

Jacob had Hunter syndrome, a disease which affects only three boys a year and which on average claims its victims' lives by the age of 13.

Mrs Wragg's mother, Gwendoline Richards, described how her daughter and the defendant "fought for control" in their relationship but that they both loved Jacob.

Mrs Richards described Wragg to police in the days after the killing as having "a soft centre which was covered by a big, gruff exterior".

She said in interview: "He was someone who had an attitude. His life has not been easy. He worked hard. He does not have a lot to say."

In court, Mrs Richards was asked if Jacob's parents both loved the youngster. She replied: "Very strongly."

On the night of Jacob's death, Mrs Richards told police: "To hear this was the best news I could have. He was not Jacob any more, he was just a shell."

Mrs Richards told the court: "It was such a shocking thing. The fact that Jacob had died, in some ways I felt he had been released from being ill.

"I loved him and I did not want him to die, but I did not want him to suffer. It's a very strange feeling. We knew he would get worse."

When asked by police about Jacob's condition, Mrs Richards said he had a cough which made him sound as if he smoked 60 cigarettes a day.

The trial was adjourned until today.