The father of a Muslim convert who joined Isis told police his son would not “hurt a tree”, a court has heard.

Jack Letts’ parents are accused of attempting to send him more than £1,700 despite it being “clear from the information available to them” that he was in the terrorist group’s Syrian territories.

The Old Bailey heard that the couple had been warned about Jack’s radicalisation after he converted to Islam aged 16, but bought him a plane ticket for a “grand adventure” in the Middle East.

In March 2015, police visited his parents’ Oxford home and issued a formal warning that they risked prosecution if they sent their son money or property.

In a statement given to officers, his father John Letts said he had enjoyed a good relationship with his “very personable, engaging and humorous” son.

Mr Letts, 58, said that as a youngster Jack had aspirations to be an artist or footballer but lost focus on his A-levels because of his obsessive compulsive disorder.

“He had a phase being obsessed with football and would sleep next to his football,” he added.

“The same thing happened with religion … he would read all things to do with Islam. Jack would want to outdo people. If he was to attempt something he would have to try to be the best at it.”

Timeline of the Isis caliphate Show all 19 1 /19 Timeline of the Isis caliphate Timeline of the Isis caliphate ISIS began as a group by the merging of extremist organisations ISI and al-Nusra in 2013. Following clashes, Syrian rebels captured the ISIS headquarters in Aleppo in January 2014 (pictured) AFP/Getty Timeline of the Isis caliphate Abu Bakr Al-Baghdadi declared the creation of a caliphate in Mosul on 27 June 2014 Timeline of the Isis caliphate Isis conquered the Kurdish towns of Sinjar and Zumar in August 2014, forcing thousands of civilians to flee their homes. Pictured are a group of Yazidi Kurds who have fled Rex Timeline of the Isis caliphate On September 2 2014 Isis released a video depicting the beheading of US journalist Steven Sotloff. On September 13 they released another video showing the execution of British aid worker David Haines Timeline of the Isis caliphate The US launched its first airstrikes against Isis in Syria on 23 September 2014. Here Lt Gen William C Mayville Jnr speaks about the bombing campaign in the wake of the first strikes Getty Timeline of the Isis caliphate Isis militants sit atop a hill planted with their flag in the Syrian town of Kobani on 6 October 2014. They had been advancing on Kobani since mid-September and by now was in control of the city’s entrance and exit points AFP/Getty Timeline of the Isis caliphate Residents of the border village of Alizar keep guard day and night as they wait in fear of mortar fire from Isis who have occupied the nearby city of Kobani Getty Timeline of the Isis caliphate Smoke rises following a US airstrike on Kobani, 28 October 2014 AFP/Getty Timeline of the Isis caliphate YPG fighters raise a flag as they reclaim Kobani on 26 January 2015 VOA Timeline of the Isis caliphate Isis seized the ancient Syrian city of Palmyra on 20 May 2015. This image show the city from above days after its capture by Isis Getty Timeline of the Isis caliphate Kurdish forces are stationed on a hill above the town of Sinjar as smoke rises following US airstrikes on 12 November 2015 AFP/Getty Timeline of the Isis caliphate Kurdish forces enter Sinjar after seizing it from Isis control on 13 November 2015 AFP/Getty Timeline of the Isis caliphate Iraqi government forces make the victory sign as they retake the city of Fallujah from ISIS on 26 June 2016 Getty Timeline of the Isis caliphate Iraqi forces battle with Isis for the city of Mosul on 30 June 2017 AFP/Getty Timeline of the Isis caliphate Members of the Iraqi federal police raise flags in Mosul on 8 July 2017. On the following day, Iraqi prime minister Haider Al Abadi declares victory over Isis in Mosul Getty Timeline of the Isis caliphate Members of Syrian Democratic Forces celebrate in Al-Naim square after taking back the city of Raqqa from Isis. US-backed Syrian forces declare victory over Isis in Raqqa on 20 October 2017 after a four-month long campaign Getty Timeline of the Isis caliphate Female fighters of the Syrian Democratic Forces celebrate in Al-Naim Square after taking back the city of Raqqa from Isis. US-backed Syrian forces declare victory over Isis in Raqqa on 20 October 2017 after a four-month long campaign AFP/Getty Timeline of the Isis caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria in January 2019 They were among the last civilians to be living in the ISIS caliphate, by this time reduced to just two small villages in Syria’s Deir ez-Zor Richard Hall/The Independent Timeline of the Isis caliphate Zikia Ibrahim, 28, with her two-year-old son and 8-month-old daughter, after fleeing the Isis caliphate, on Saturday 26 January 2019 Richard Hall/The Independent

Mr Letts told how Jack’s old friends faded away and he gathered new associates from a mosque who would occasionally visit the family home.

He claimed his son had been “very much a pacifist” and would not even “hurt a tree”, but became upset over the Syrian civil war and the suffering of its people.

Mr Letts told police Jack went to Jordan because he was keen to learn Arabic, but the court previously heard that he was warned over his son’s radicalisation.

Anwar Belhimer, a friend of Jack’s from the mosque, told Mr Letts that Jack had been using extreme language and appeared to have been radicalised by others, including a man called Abdullah.

Mr Belhimer urged him to confiscate his son’s passport and told Jack that he would not help the Syrian people by fighting, but Jack left the UK in May 2014, aged 18.

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

Mr Letts told police that the teenager became more “reserved” in communications and stopped telling his parents that he loved them in phone calls.

But he claimed he had no reason to believe Jack had been involved in fighting, as his son had said he was not with Isis.

The court heard that in May 2015 – two months after the parents were first interviewed by police – Jack posted a photo of himself on Facebook wearing combat fatigues while standing by a dam in Raqqa, Isis’s de-facto capital.

And in July of that year, he wrote on Facebook that he wanted to behead an old school friend and other soldiers in a “martyrdom operation”, a court has heard.

The jury was shown a photo of Jack Letts posing at the Tabqa Dam outside Raqqa (Facebook)

The jury was told that by the time his parents attempted the money transfers they were charged over, they knew Jack had married someone in Iraq and journeyed onwards into Isis territory.

Prosecutor Alison Morgan QC said: “It was not open to these defendants to take the law into their own hands and to send money to their son, whatever their own reasons and motives may have been.”

The defendants, of Chiswell Road in Oxford, deny three charges of funding terrorism.

The trial continues.