A young man accused of planting a home-made bomb on the London Tube has refused to explain himself at his trial.

Damon Smith was 19 when he allegedly packed a rucksack with explosives and ball-bearing shrapnel and left it on a train timed to go off within minutes.

He allegedly referred to an al Qaida article entitled Make A Bomb In The Kitchen Of Your Mom as he put together the device with a £2 clock from Tesco.

A shopping list for "pressure cooker bomb materials" was also allegedly found on an iPad ending in a note to "keep this a secret between me and Allah #InspireTheBelievers".

Jurors at the Old Bailey have been shown CCTV charting Smith's journey on the London Underground on the morning of October 20 last year.

There were at least 10 passengers in the Jubilee Line carriage when he left the device, the court has heard.

Had it worked, it would have exploded just as people were being ordered off the platform after the train arrived at North Greenwich, the jury was told.

Upon his arrest, the autistic student admitted making the device but claimed he only meant it to spew harmless smoke as a prank.

After the prosecution closed its case, Smith's lawyer, Richard Carey-Hughes QC, announced his client's decision not to give evidence.

Judge Richard Marks QC told jurors they could draw such inferences from his failure to go into the witness box as they saw fit.

He told jurors the defence case would continue and they would probably begin deliberating on their verdict on Wednesday.

Smith, now 20, of Rotherhithe, south London, denies possession of an explosive substance with intent, contrary to the Explosive Substances Act 1883 but has admitted the lesser offence of perpetrating a bomb hoax.

Jurors heard extracts from a psychiatric report by Dr Ian Cumming, who confirmed the defendant had an autistic spectrum disorder.

Smith told him of his longstanding interest in weapons, bombs, guns, knives and knuckledusters.

At the age of 12, he got a police baton and nunchucks from the US.

Smith said he looked up making a bomb when he was aged 10 and at 14 a friend showed him the Anarchist Cookbook via Skype.

He said he liked making bombs because it was "something to do when he was bored".

The former altar boy said he was also interested in Islam and collecting Star Wars figures.

He told the psychiatrist he had thought about putting a bomb in a park but decided a train would be "more funny" to delay passengers.

According to the report, he had no conception that it might cause harm.

Jurors were also shown extracts of other videos Smith posted on YouTube.

In one he is seen playing with a dog, "Skippy", and in another he demonstrates how to draw Bart Simpson.

In a third video entitled My Perfumes, Smith shows off his collection of scents including Paco Rabanne and James Bond.