A gun-obsessed jihadi who claimed to be on the MI5 payroll has been jailed for four and a half years for having a stash of terror training videos.
Muslim convert Mustafa Abdullah, 34, was stopped at Gatwick Airport last year as he returned from a trip to Syria.
Police examined his phone and computers and uncovered gun instruction videos and audio files on guerilla warfare and combat equipment.
The jury was also shown a photograph from April last year of Abdullah with an automatic rifle on his shoulder, recovered from his mobile.
The appliance engineer, of Binfield Road, Stockwell, south-west London, denied 14 counts of possessing terrorism documents or records and one of possessing a gun for a terrorism purposes.
He told jurors MI5 paid him £10,000 for helping them and insisted he only went to war-torn Syria to do humanitarian work.
However, the jury deliberated for more than 12 hours to find him guilty of 13 offences of possession of documents likely to be useful to a person preparing an act of terrorism. He was cleared of the remaining charges.
Jailing him, Judge Gerald Gordon said if he had not been arrested he had no doubt Abdullah would have returned to Syria.
Judge Gordon said the material found on Abdullah's devices "formed part of a collection, a veritable reference library, of material expressing twin interests - interest in guns, gun training, violence, fighting and death, and on the other hand extremist radical Islam".
He added: "The picture is a depressing one."
Abdullah had been radicalised while serving a six-year sentence in youth custody and had been convicted on a similar terror offence before.
He added : "You have still learnt precisely nothing - except what not to do to be detected in the future."
Prosecutor William Emlyn Jones had said the defendant left one of his Islamic wives, Souriya, around November 2013, intent on martyrdom in the north-west region of Syria where the conflict was intense.
Prompted by the news that some of his "close brothers" had died, Abdullah said he had "set my mind that I want paradise, and paradise is not cheap", the court heard.
Then, in May last year, he made his way back by flying from Turkey to Sweden and then on to Britain.
He was stopped at Gatwick and his phone was seized, leading to the discovery of a large number of videos, audio files and documents on the SD card.
They demonstrated his interest in two things - weapons, specifically firearms and how to use them, and radical, violent and fundamentalist Islamic ideology - "a dangerous mixture".
Abdullah told police at the airport that he was born in the UK of Christian Jamaican parentage but converted to Islam around 2000 and took several wives under Islamic law.
He admitted being in Turkey and Syria but said he went to do aid work in Aleppo and Latakia.
After the phone was examined, Abdullah was arrested in October last year when he claimed that he had not known any of the training videos were on it.
Police also uncovered more material on phones, tablets and a laptop computer at Abdullah's home, jurors were told.
Giving evidence in his defence, Abdullah said he first became involved with the British security service between January and August 2008.
His lawyer Andrew Hill asked: "What was the purpose of the contact?"
Abdullah replied: "Basically, they were saying, 'can you spy for us?'.
"I said Muslims don't spy, however, I will assist you. I don't hang around with people like that but if I do, I will let you know."
Abdullah told jurors he was paid £10,000, adding: "I didn't need the money but they wanted to give it, so I took it."
Three months before he went to Syria, MI5 agent "Graham" called him and asked for a meeting, but he rebuffed him, the defendant said.
Abdullah, who has several children by various wives, has a previous conviction for possessing documents useful for terrorism.
In September 2006 he was arrested under the Terrorism Act and jailed for two years after pleading guilty at Woolwich Crown Court.
The Old Bailey was told he also had an "appalling" criminal past with convictions for wounding and robbery.
The defendant told jurors of his long-standing fascination with guns, which he compared with his wife's love of handbags.
He said: "My wife said to me, 'it's like I like handbags'. If I was in America I could fire guns all day, no problem. I love guns. I cannot explain it. They look nice."
Abdullah and his wife were photographed on a gun range in the United Arab Emirates and, while working in Yemen in 2012, he bought a gun with a licence.
He told jurors: "You can buy a handgun in the market place like you can buy a cabbage."
But asked if he ever had any intention of harming anybody in this country, Abdullah said: "I'm your local engineer. When I come into your home and fix your appliances, I will make you laugh."
Abdullah made no reaction as he was sent down to begin his sentence.
Afterwards, a Crown Prosecution Service spokesman said: "The evidence found on Mustafa Abdullah's phone strongly indicated that he was preparing or planning an act of terrorism. Many of the videos had links to jihad and detailed how to use weapons with the intention being to kill.
"He had claimed to have been travelling to Syria for humanitarian reasons, however, pictures found on his phone showing Abdullah holding an automatic assault rifle suggested a more sinister purpose to his visit. There was also no evidence on his laptop, tablets and phones of having carried out any research into humanitarian work.
"The most chilling of the articles found was that of an Arabic lecture containing detailed instructions on how to research and carry out a terrorist attack on a city centre."
Commander Richard Walton, head of the Met's Counter Terrorism Command, said: "Our message is clear; any extremists who have travelled to Syria and return to the UK will be investigated and where we find any evidence that they are involved in terrorist activity - whatever that may be - we will look to arrest and prosecute them."