This is the smiling, former-altar boy who has been jailed for 15 years after he almost blew up North Greenwich station.

Damon Smith built the device at home with a £2 clock from Tesco after finding an online al Qaida article entitled Make A Bomb In The Kitchen Of Your Mom.

The 20-year-old student packed a rucksack with an explosive filled with ball bearings shrapnel on the morning of October 20 last year.

Caught on CCTV, the autistic would-be bomber left the bomb on the floor of the Jubilee Line tube, timed to go off when it arrived at North Greenwich.

Damon, of Abbeyfield Road in Rotherhithe, smiled in the dock as Judge Richard Marks QC sentenced him today (May 26) to 15 years in a young offenders' institution with an extended period of five years on licence

He also smiled throughout his police interview when he was arrested and admitted to making the bomb, but claimed it was just supposed to be a Halloween joke.

He told police he had been inspired from watching someone on a YouTube channel called Trollstation doing a bomb prank.

His defence was rejected by the jury and he was found guilty of possession of an explosive substance with intent following a trial at the Old Bailey.

Judge Marks told the defendant: “Quite what your motives were and what your true thinking was in acting as you did is difficult to discern with any degree of clarity or certainty.

“Whatever the position, the seriousness of what you did cannot be overstated, not least against the background of the fear in which we all live from the use of bombs here and around the world, an all too timely reminder of which were the events in Manchester earlier this week.”

Smith told police he was interested in Islam but denied being an extremist, even though he had posed next to an image of the Brussels-born Islamic terrorist alleged to have masterminded the attacks in Paris in November 2015.

In his defence, extracts of a psychiatric report were read out confirming an autism spectrum disorder.

He had been interested in bomb-making since the age of 10 and said it was "something to do when he was bored".

Smith, who grew up living with his mother in Newton Abbot, Devon, said he had thought about putting a bomb in a park but decided it would be "more funny" to delay train passengers.

The driver of the tube saw the rucksack with the bomb, but thought it was lost property and took it with him to North Greenwich.

It was only when he saw the wires sticking out of the bag did he realise the danger he was in and the station had to be evacuated.

The defendant went on to college and, on returning home in the evening, checked the internet for news of what he had done.

During a search of his home, officers found a blank firing pistol, a BB gun, a knife and knuckleduster.

On his social media accounts they discovered that Smith had 'liked' a number of videos relating to explosions and had shared articles about the current threat level.

More significantly, officers discovered a number of shredded documents. These were carefully reconstructed by a forensic scientist and found to be pages that gave instructions on bomb-making.

Commander Dean Haydon, Head of the Met's Counter Terrorism Command, said: “We have seen this week the horrifying impact a bomb can have.

“And whilst there is no connection between Manchester and Greenwich it brings into stark reality just how devastating it could have been. The bomb Smith made was a viable device, but it failed to detonate, which was our good fortune.

“I would like to praise the public who informed the train driver of the abandoned bag; because of their quick intervention we were able to make it safe and identify Smith.

“At this time of heightened security we ask everyone to remain calm but alert, to report anything that causes concern immediately; if you have suspicions about someone's behaviour call police.”