Damon Smith jailed for leaving bomb on Jubilee Line Tube train

An autistic man who planted a home-made bomb on a busy Tube train smiled in the dock as he was jailed for 15 years.

Damon Smith, 20, packed the device with gunpowder and metal ball bearings and left it on a Jubilee Line train on 20 October last year.

Had the timer not failed, the bomb would have exploded just as people were being ordered off the platform at North Greenwich station.

Smith claimed the bomb was a Halloween prank during his trial at the Old Bailey, but earlier this month he was found guilty of possession of an explosive substance with intent.

Smith will serve his sentence in a young offenders’ institution, with an extended period of five years on licence.

Judge Richard Marks, QC, 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’s defence had argued that the root cause of his actions were in his autistic disability. The court heard experts could not agree on his future risk to society.

He was said to have been inspired after watching a bomb prank on YouTube channel Trollstation.

Smith’s barrister, Richard Carey-Hughes QC, told the court Smith was "sorry" for the fear and disturbance he caused and has "learned his lesson".

CCTV footage of Smith showed him travelling on the Jubilee Line before leaving the train without the rucksack containing the bomb.

There were at least 10 passengers in the carriage at the time, some of whom spotted the abandoned rucksack and alerted the driver.

The court was told that the driver believed the bag was lost property and took it into his cab to continue the journey to North Greenwich.

During the journey the driver noticed wires coming out of the rucksack and raised the alarm.

Smith checked the internet for news of his "prank" when he got home later that day.

Smith told the arresting counter-terrorism officers that the device was only meant to spew harmless smoke as a Halloween joke.

Police found materials at his home in Rotherhithe, south London, revealing his fixation with guns and explosives.

Officers seized a blank-firing pistol and a BB gun, both bought legally, as well as a knuckleduster and a knife.

Police also found scraps of paper with bomb-making instructions and a "shopping list" of components.

Smith told officers he was interested in Islam, but was not an extremist. He had posed next to an image of the man alleged to have masterminded the November 2015 terrorist attacks in Paris.

(c) Sky News 2017: Damon Smith jailed for leaving bomb on Jubilee Line Tube train