Dramatic video shows the moment a smiling teenage hitman was arrested by armed police at a hotel room in his boxer shorts.

Johannes Natland, then aged 18, flew into Britain from Norway to assassinate a target in the UK on behalf of an organised crime group backed by Iran, the Old Bailey has heard.

He was thwarted when he was arrested at the Briar Court Hotel in Huddersfield, West Yorkshire, on March 19 last year, two days after his arrival.

Bodyworn video shown to a jury today shows the alleged teenage assassin answering the door at 5.15am in his boxer shorts before 'pretending to shoot' an officer, muttering 'that was fun'.

The footage showed Natland acting as though he was wielding a firearm before the officers pushed him against the wall and handcuffed him.

The officers brought jeans to him in the corridor and he smiled, telling one officer: 'You happy Kev? Please say you're happy Kev. Give me a smile Kev. You smiling?'

He added in Norwegian: 'That was fun, like' and in English: 'Funny, eh? What the f**k is this shit?'

Police found a semi-automatic pistol, a revolver and 12 rounds of live ammunition in his possession, as well as £2,000 in cash.

They also discovered a four-pack of Corona beer with two bottles empty and a large bottle of Desperados beer which was still full, along with two unopened cans of Blue Edition Red Bull.

There was also a packet of Marlboro cigarettes, two lighters and a vape kit.

Natland was expecting to be paid more than £20,000 and 'neither knew, nor cared' who the target was, the court was told.

After arriving at Manchester airport from Stavanger, south-west Norway, Natland sent messages to his on-off girlfriend saying it 'will be cool' to 'finally kill someone' and the pair should 'celebrate' if he didn't get caught, it was heard. 

He was allegedly recruited by the Swedish Foxtrot Network, which has been used by the Iranian regime and is sanctioned by the US and UK.

The group recruits children as young as 13 for jobs including murder, arson and bombings, often targeting vulnerable youngsters.

Interviewed by a nurse in custody, Natland said he had a history of cannabis use and street-bought oxycodone, a synthetic opioid.

He was not found to have any acute mental health concerns and was found fit to be interviewed.

The court heard Natland has a history of suffering from drug-induced psychotic episodes.

He was discharged from a psychiatric unit in Norway, six weeks before he travelled to Britain but his mental state at the time was not disordered and no active psychotic symptoms have been identified from that time, the experts agreed.

Natland has pleaded guilty to possession of a 9mm semi-automatic pistol and a revolver along with 12 rounds of live ammunition but denies conspiracy to murder.

The trial continues.