Convicted killer Ian Stewart, who is on trial for the murder of his wife, was accused today of having her cremated "so there would be very little that could come back and bite you".

Stewart, who is 61 and from Letchworth, is accused of killing his wife Diane in Bassingbourn in 2010, six years before he murdered his fiancée, the Royston children's author Helen Bailey.

At the time, Diane's death was attributed to sudden unexplained death in epilepsy (SUDEP).

A neuropathologist was asked to examine preserved parts of Mrs Stewart's brain, which had been donated to medical science.

He told Huntingdon Crown Court he found evidence of a lack of oxygen to her brain for between 35 minutes and an hour before her death.

Stuart Trimmer QC, prosecuting, told the defendant: "You had Diane Stewart cremated so there would be very little that could come back and bite you."

Stewart replied: "The cremation was a joint decision with the boys and if I was thinking that way I wouldn't have agreed to keep the brain and heart."

Mr Trimmer said that Stewart's 999 call in 2010, in which he said his wife had had a fit, was "just a lying charade", adding: "You're a devious man, Mr Stewart."

Stewart replied: "No."

During Stewart's trial for the murder of Ms Bailey in 2017, jurors were told her body was discovered in a cesspit at the £1.5 million home she shared with Stewart in Royston.

A forensic pathologist found it was most likely she was suffocated while she was sedated by drugs.

Mr Trimmer said: "Is it not very surprising that both Helen Bailey and Diane Stewart are individuals whose death was caused by a similar mechanism in the view of the professionals?"

"Only some of the professionals," Stewart replied.

The prosecutor suggested Stewart was "a man capable of extreme and callous violence".

Stewart replied: "No."

The court was previously told that Stewart benefitted financially from Diane's death, receiving a total of £96,607.37, which included money from her bank accounts and £28,500.21 from a life insurance policy..

Asked by Amjad Malik QC, defending, if he wanted the money, Stewart said: "No, I don't want that money, I didn't need that money, it was for the boys' futures."

The defendant said he bought a red two-seater MG car after his wife's death as "it's what Diane and I had up until (their son) Jamie was born".

"This was the red one we always wanted, it was just a memory."

Asked what the memories were of, he added: "Time spent with Diane. We had lots of time going on day trips to car events."

Stewart previously told jurors that he returned from Tesco to find his wife collapsed in the garden, and said he attempted CPR on her himself before dialling 999.

Paramedics later arrived and they attempted CPR.

Mr Malik asked: "When they carried out CPR, what did you think about the way they had done it?"

Stewart said it was "just different, staccato".

He said: "I thought I hadn't succeeded as I had done it wrong. That was in my mind straight away.

"I had failed, I hadn't saved Diane's life basically."

Mr Malik said: "The prosecution say you caused Diane Stewart to die and that you carried out an action, asphyxiation, upon her. What do you say to that?"

Stewart said: "Total rubbish. I was trying to save her life that day, the exact opposite of what they say happened.

"I was trying to save her life, get her to breathe again. She's the mother of (their sons) Jamie, Oliver and she was my wife."

Stewart denies the murder of his wife.

The trial continues.