A MUSLIM convert dubbed Jihadi Jack was a "personable" young man who used to sleep next to his football before he switched his obsession to religion, a court has heard.

After he travelled to Syria, Jack Letts' parents also noticed he became more "reserved" and no longer told them "I love you" in his calls home, the Old Bailey was told.

Organic farmer John Letts, 58, and his wife Sally Lane, 56, are on trial accused of sending him money despite having every reason to believe he had joined Islamic State.

Former Cherwell School pupil Jack Letts was just 18 when he left home in Oxford and travelled abroad, married the daughter of a high ranking tribesman in Iraq and moved to Syria, jurors have heard.

In March 2015, police visited his parents' home and formally warned them that they risked prosecution if they sent their son money or property.

In a police statement, John Letts said he had enjoyed a good relationship with Jack who was "very personable, engaging and humorous".

As a youngster, he had aspirations to be an artist or footballer but lost focus on his A Levels because of his obsessive compulsive disorder (OCD).

He said: "He had a phase being obsessed with football and would sleep next to his football.

"The same thing happened with religion.

"He started to become interested in what it is to be a Muslim some three years ago.

"He would read all things to do with Islam.

"Jack would want to out-do people.

"If he was to attempt something he would have to try to be the best at it."

John Letts told how Jack's old friends faded away and he had new friends from the mosque who would occasionally visit the family home in Oxford.

He said Jack had been "very much a pacifist" and would not even "hurt a tree" but became upset at the situation in Syria and the suffering of its people.

He said: "As a Muslim, I think Jack felt this deeply."

John Letts told police his son went to Jordan because he was keen to learn Arabic.

Before he left, the defendant told how his friend Anwar Belhimer had expressed "concern" that Jack wanted to go to Syria and had been associating with someone called Abdullah who appeared to have extreme views.

About four months after his departure, John Letts learned from Lane that their son had in fact moved on to Syria, the court heard.

He told police: "He seemed happy but reserved.

"We always used to say 'I love you' before hanging up but he avoided saying it."

John Letts and former fundraising officer Lane have denied three charges of funding terrorism.

John Letts told police he had no reason to believe his son had been involved in fighting, having said he was not with Isis.