The ex-wife of murder case foster father Sion Jenkins revealed he had a temper and could have killed their foster daughter over a petty squabble, the Old Bailey heard.

Lois Jenkins expounded a theory she believed could have prompted Jenkins into battering Billie-Jo Jenkins with a metal tent spike.

She said another daughter, Annie, was a bright girl but was finding it difficult to deal with Billie-Jo, who would embarrass and humiliate her on occasion.

On the day of the murder, Annie had been passed over to paint the patio doors at their home in Lower Park Road, Hastings, in favour of 13-year-old Billie-Jo.

A police report, taken down in a series of notes read in court yesterday, stated: "Lois has a theory that if Sion lost it, it would have been about Billie-Jo smugly painting the patio doors, something Annie desperately wanted to do. Billie-Jo winding Annie up (confirmed by Annie), making her depressed. Sion suddenly thinking what am I doing?' A gesture by Billie-Jo to Annie, rubbing it in, as she was prone to do - enough to make Sion snap."

Billie-Jo was struck at least five times as she painted the patio doors on February 15, 1997.

Jenkins, 47, the former headteacher designate at William Parker School, in Hastings, was found guilty of Billie-Jo's murder at Lewes Crown Court in 1998. The conviction was quashed on a second attempt by three appeal court judges in July and a retrial was ordered.

Mrs Jenkins, giving evidence for a third day yesterday via video link from a secret location, denied lying to police to get her ex-husband convicted of murder.

Defence counsel Christopher Sallon QC suggested Mrs Jenkins feared that if Jenkins was cleared of murder it would aid his bid for access to their children and jeopardise her plans to move abroad with her daughters.

He said that Mrs Jenkins had already been convinced of his guilt after being given scientific evidence by police early on in the inquiry.

Mr Sallon said the police account of daughters Lottie and Annie, who were both with him on the day of the murder, could have led to Jenkins walking free if they had given evidence at his original trial.

The defence team asked to interview the girls to verify their version of events and to determine whether they should be called to give evidence at Jenkins' original trial, Mr Sallon said.

However, Mrs Jenkins declined the request saying they were too vulnerable and, as a result, they did not give evidence.

Jenkins denies murder. The case continues.