Dramatic moment terror plotter who planned to behead Theresa May is dragged to the ground by undercover police during arrest

This dramatic aerial footage shows the moment undercover police surrounded and arrested an Islamic State terrorist who plotted to behead Prime Minister Theresa May.

Naa'imur Rahman, 20, could be facing life in prison after he planned to blast his way into Downing Street, kill guards and then storm Number 10 armed with a suicide bomb, a gun and knives.

But his plot was foiled following an undercover investigation by the Metropolitan Police, MI5 and the FBI.

Drone footage today released by Scotland Yard shows Rahman being arrested by counter terror officers after collecting what he thought was an explosives-packed jacket and rucksack on November 28, 2017.

Police images also show Rahman's possessions lined with replica improvised explosive devices and a replica bomb intended to be used in the attack.

Following an Old Bailey trial, Rahman, from Finchley, north London, was found guilty of preparing acts of terrorism in Britain.

As part of his attack Rahman had sought to detonate a bomb near to Downing Street before using the ensuing chaos to gain access to Number 10.

Rahman, originally from Birmingham, plotted his attack over the course of two years after his extremist uncle was killed in a drone strike while fighting for IS in Syria.

However he was snared by a network of undercover counter-terrorism officers.

Unbeknown to Rahman, as he was putting his plans together he was confiding online with role-players from the Met Police, MI5 and the FBI who introduced him to officers from the Met's Counter Terrorism Command.

Rahman met with these officers on a number of occasions as he sought to obtain explosives for the attack.

Following his uncle's death, Rahman turned to the internet for help in his attack plans.

He made contact with an FBI agent posing as an IS official online, who introduced him to an MI5 role-player.

By early November last year, he appeared settled on an attack on 10 Downing Street with a suicide bomb, gun or knife.

He told an undercover officer: "(God willing) will be very big if I'm successful. I can't mess up. I can't get (martyrdom) if I get caught."

On November 18 last year, Rahman carried out reconnaissance around Whitehall, CCTV footage showed.

Two days later, he bought a rucksack from Argos before meeting an undercover officer in Brixton for it to be fitted with explosives.

On November 28 last year, the officer handed back Rahman's rucksack and coat, now packed with dummy explosives, and replica pepper spray.

Rahman told the officer he was "good to go" but was arrested as he walked away carrying the fake bomb, in Kensington.

Images released by the Met show Rahman's rucksack with a replica bomb intended to be used as a bomb in a bag, and his jacket fitted with replica improvised explosive devices.

Met Police deputy assistant commissioner Dean Haydon said: “Rahman is an extremely dangerous and determined individual.

“Rahman’s target was the Prime Minister but he had no qualms about killing innocent bystanders in the process of reaching her.

"In fact, at one point he told a covert counter terrorism officer that even if he could not reach the Prime Minister, he just wanted to strike fear into people."

Rahman came to the attention of police in July last year when he complained he was being blackmailed, but failed to attend an appointment.

In August last year he was arrested on suspicion of sending indecent images to underage girls, but never charged.

An examination of his mobile phone raised concern he may be harbouring extremist views.

DAC Haydon continued: “Every day the counter terrorism network employs a plethora of tactics to investigate terrorism and keep the public safe from terrorists.

"Covert policing is a crucial tactic and in this case, it enabled us to understand fully what Rahman intended to do and how serious he was about doing it.

"Covert officers were able to gather the strong evidence for the prosecution, and it follows that the jury have found Raham guilty.

“This case is a reminder of the continuing threat from terrorism and the need for us to all be vigilant and report any suspicious behaviour.”

Rahman is due to be sentenced on August 31.

Additional reporting by Press Association.