A SENIOR judge has hailed the “extraordinary” investigation which brought a Daesh terrorist to justice for a plot to kill Prime Minister Theresa May.

Naa’imur Zakariyah Rahman, 20, could be facing life behind bars for planning to bomb the gates of 10 Downing Street, kill guards and then attack Theresa May with a knife or gun.

He had pledged allegiance to Daesh and collected what he thought was an explosives-packed jacket and rucksack when he was arrested last November.

The drifter, originally from Birmingham, thought he was being helped by a Daesh handler when in fact he was talking to undercover officers.

Rahman, from Finchley, north London, was found guilty on Wednesday of preparing acts of terrorism in Britain. The verdict followed an Old Bailey trial. Midway through the trial, he admitted helping his friend Mohammed Aqib Imran to join Daesh in Libya by recording a sponsorship video.

Adjourning sentencing until August 31, trial judge Mr Justice Haddon-Cave paid tribute to the way the “extraordinary” case had been “robustly investigated, prepared and presented”.

He added that it would be “extremely reassuring for the public as to how this remarkable investigation has been conducted”. Rahman was snared by a network of undercover counter-terrorism officers from the Metropolitan Police, the FBI and MI5. Deputy Assistant Commissioner Dean Haydon, from Scotland Yard, said: “If he had got hold of a genuine bomb, a gun, or a knife, we would have been talking about an individual who could have killed, injured and maimed a number of individuals in Whitehall.”

Rahman came to the attention of police in July last year. 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 might be harbouring extremist views.

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

The defendant revealed his plans, saying: “I want to do a suicide bomb on Parliament. I want to attempt to kill Theresa May.”

Last November, an undercover officer gave Rahman a rucksack and coat packed with dummy explosives and replica pepper spray. He was arrested in Kensington as he walked away carrying the fake bomb.

Sue Hemming, from the Crown Prosecution Service, said: “Naa’imur Rahman planned a terror attack at the heart of British democracy.

“Thanks to the work of the police and security services, he would never have succeeded.”