Islamic State flag and items which were used by Islamic State militants are seen at a museum in Erbil. File picture: Azad Lashkari/Reuters

London - The tearful mother of the Muslim convert known as Jihadi Jack told a court on Tuesday of her horror when the teenager rang to tell her: ‘Mum, I’m in Syria.’

Sally Lane said she screamed: ‘How could you be so stupid? You will get killed. You will get beheaded.’

Lane, 56, wept as she also spoke of her son Jack Letts’ marriage while he was in the Middle East.

Then 18, he had left home in Oxford in 2014 and travelled to Jordan and Kuwait before marrying the daughter of a high-ranking tribesman in Iraq.

He moved to Syria and told his parents he was deep in territory held by Islamic State. Lane, a former fundraising officer, and her husband John Letts, 58, are on trial accused of sending or trying to send £1,723 to their son even though they had reason to believe he had joined the terror group.

They ignored repeated warnings that they faced prosecution if they tried to help their son while he was in IS territory, it is alleged. Giving evidence in her defence at the Old Bailey, Lane told jurors that her son initially ‘seemed like he was enjoying himself’ in Jordan and Kuwait.

On September 2, 2014, he called her to say he was in Syria. ‘I was horrified. I screamed at him,’ she said.

He phoned again on September 24 and said he had been ill.

‘He did not say exactly where he was. He tried to be reassuring, saying, “It’s not a war zone”. Someone had looked after him,’ Lane said. The couple’s home was raided by police on March 31, 2015.

A month later, Lane attempted to use a £5,000 inheritance from her son’s grandfather ‘as a bribe’ to encourage him and his new wife Asmaa to get ‘somewhere safe’. But on May 21 he posted a photograph of himself in Raqqa, an IS stronghold in Syria.

Lane said she felt ‘sick’ when on July 30 her son appeared to threaten to behead an old school friend, Linus Doubtfire, who had posted a photograph on Facebook after he passed an Army commando course. Next to the picture, Jack Letts commented: ‘I would love to perform a martyrdom operation in this scene.’

Lane told the jury: ‘It was so out of character. He had never said anything violent before.

‘I just thought it didn’t sound like him.’

Questioned on whether she thought money she and her husband sent their son would fund terrorism, she replied: ‘No. I actually thought it might enable Jack to get to Lebanon.’

John Letts, an organic farmer, said he would never have forgiven himself if his son had died in the Middle East and he had done nothing to protect him.

He claimed he was told by police that no court in the land would convict him for helping his son get out of Syria.

The couple’s lawyers say counter-terrorism police gave them the ‘green light’ to send money.

Letts, 58, told police that he wanted Jack to give himself up to the British.

‘But that is the hard bit, how do you do that?’ he said.

‘You’ve still got to go through the borders, you have still got to get somewhere safe. In the meantime, you know you can’t sleep, this is the son that you nurtured, and it’s horrible.’

Letts and Lane, from Oxford, deny three charges of entering into a funding arrangement for the purposes of terrorism.

The trial continues.

Daily Mail