Media playback is unsupported on your device Media caption CCTV captured the moment Damon Smith left the bomb on a busy Jubilee line train

A man has been found guilty of trying to cause "maximum damage" by making a bomb filled with ball bearings and leaving it on a Tube train.

Damon Smith put his homemade device into a rucksack and left it on a Jubilee line train in October.

The 20-year-old had admitted perpetrating a bomb hoax but claimed it was a prank.

Had it worked, the bomb would have exploded just as commuters were leaving the North Greenwich station platform.

Former altar boy Smith built the device with shrapnel and a £2 clock from Tesco after Googling an al-Qaeda article on bomb-making.

The Old Bailey was told the student, who has an autistic spectrum disorder, had a keen interest in guns, bombs and other weapons, which may have been a function of the condition.

His lawyer told the trial he was no "hate-filled jihadi" and never meant to harm anyone.

However, the jury convicted him of making or possessing an explosive substance with intent to endanger life after two hours of deliberations.

The Met said he was not charged under the Terrorism Act because there was not enough evidence that his crime was politically motivated.

Image copyright Met Police

On 20 October, the defendant - then aged 19 - left the rucksack containing the bomb on the train.

Passengers handed it to the driver who then realised as he was approaching the station it contained explosives.

Smith then went to university and when he returned home that evening, checked the internet for news reports about what he had done.

When he was arrested, he admitted making the bomb, but said he had meant for it to have been a Halloween prank and that he had been inspired by a YouTube video.

Jurors were also told Smith had professed an interest in Islam as he felt it was "more true" than Christianity.

He "did not really practise Islam, although he read the Koran and sometimes prayed in the morning when it was convenient but did not hold extreme views", lawyers said.

Media playback is unsupported on your device Media caption Police interview with Tube bomber Damon Smith

Image copyright Julia Quenzler Image caption Throughout the trial, Smith was seen smiling which jurors were told was part of his autism

Jurors heard he had posed next to an image of the Brussels-born Islamic terrorist alleged to have masterminded the attacks in Paris in November 2015, but had denied being an extremist.

His lawyer, Richard Carey-Hughes QC, said there was "no evidence that he changed from clinging to his mother's apron strings to a soldier of Islam and a would-be soldier".

Image copyright Met Police Image caption Smith used various materials to make his homemade device

The court heard Smith had been interested in making bombs since the age of 10 and said it was "something to do when he was bored".

He was also shown the Anarchist Cookbook at 14 by a friend.

During a search of his home in Rotherhithe, south London, officers found a shredded article on how to build a bomb and a "shopping list" of bomb materials was found on his iPad.

A blank firing pistol, a BB gun, a knife and knuckleduster were also discovered.

Image copyright Met Police Image caption Guns were found at Smith's house

Cdr Dean Haydon, from the Met's Counter Terrorism Command, said: "It is hard to believe that leaving what has been described as an improvised explosive device on a Tube train, on a weekday morning, can be construed as anything but an attempt to endanger life.

"It is fortunate that the device failed to work and that no-one was injured."

Smith will be sentenced on 26 May.