An Islamic State fanatic plotted to assassinate Prime Minister Theresa May in a suicide attack on 10 Downing Street, a court has heard.
Naa'imur Zakariyah Rahman, 20, was encouraged to cause carnage in Britain by an uncle who had joined IS and died in a drone strike in Syria, jurors were told.
He allegedly thought he was just days away from inflicting "lethal violence" with a blade and explosion before his arrest last November.
But his plan was uncovered by an MI5 agent who posed as a senior IS official in Syria, the Old Bailey heard.
Prosecutor Mark Heywood QC read out Telegram chat in which Rahman was allegedly snared by the fake Amir.
On September 14 last year, Rahman said: "Can you put me in a sleeper cell ASAP?"
"I want to do a suicide bomb on Parliament. I want to attempt to kill Theresa May."
The next day, he said: "My objective is to take out my target. Nothing less than the death of the leaders of Parliament."
The court heard Rahman went on to praise the Manchester arena bomber, saying he "did well".
He allegedly said he thought about wearing "a vest", driving past Parliament and "pushing the button" to "clear the entire block".
Jurors heard he said: "Everyone inside, including the Prime Minister would be dead."
Rahman talked about the MI5 building but allegedly said: "Getting outside Parliament when all the leaders are there is simple, you can walk right outside."
On September 23 last year, Rahman also said he had an idea based on what his uncle had told him about the IS development of poison, jurors were told.
Rahman is accused of conducting reconnaissance, recording a pledge of allegiance, and delivering a rucksack and jacket to be fitted with explosives.
Mr Heywood told jurors: "His settled conclusion was that lethal violence here, directed at the very heart of the United Kingdom Government, was the only effective way to pursue his intentions.
"Before his arrest prevented it, he was, he believed, just days away from his objective, which was no less than a suicide attack, by blade and explosion, on Downing Street and, if he could, upon the Prime Minister Theresa May herself."
He said Rahman planned a full frontal attack and fully expected to die.
The defendant is also accused of helping his friend Mohammad Aqib Imran, 22, join IS in Syria by recording a sponsorship video.
Mr Heywood said the men knew each other well and shared the same "warped ideology".
On Imran, he said: "He elected to travel and set about assembling money, acquiring a fake passport, engaging in research and otherwise equipping himself with the information and means to travel aboard for violence for terrorist purposes.
Rahman, from Finchley, north London, has denied two counts of preparing terrorist acts.
Imran, of Sparkbrook, Birmingham, has pleaded not guilty to preparing terrorist acts and possessing a terrorist document on his Kindle entitled How To Survive In The West - A Mujahid's Guide 2015.