An Islamist suicide plot to kill Prime Minister Theresa May with a bomb attack on Downing Street was foiled after British police arrested the alleged conspirators.
Police and security services believe the plotters planned to detonate an improvised explosive device at the gates of the prime minister's official residence and calculated the ensuing chaos would open an opportunity to kill Mrs May.
Such is the seriousness of the plot that the director general of MI5, Britain’s domestic security agency, briefed cabinet ministers on the plans hours before the suspects appeared at Westminster magistrates court.
Naa'imur Zakariyah Rahman, 20, from north London, was charged with preparing acts of terrorism and remanded in custody during a court hearing. Mohammed Aqib Imran, 21, from Birmingham, is accused of trying to join Islamic State and preparing acts of terror.
Rahman is also charged with assisting Imran in terror planning.
As outlined in Westminster Magistrates' court today, the plan had been to bomb Downing Street's gates before attacking Theresa May with a knife and suicide vest inside Number 10.
The pair were arrested in raids by the Met's Counter Terrorism Command in London and Birmingham on 28 November.
Britain faces the most acute threat ever from Islamist militants seeking to inflict mass attacks, often with spontaneous plots that take just days to bring to execution, the head of the MI5 said in October.
After five terror attacks that killed 36 people in British cities, this year has seen the deadliest spate of violence since the London “7/7” bombings of July 2005. The security services including the MI5 chief have warned there is no let up in the danger levels. Mr Parker has said the number of plots uncovered was at the highest tempo he had seen in 34 years in security.
In 1991, the Irish Republican Army (IRA) launched a mortar bomb attack on Number 10. John Major, the prime minister at the time, was inside but not hurt.
The IRA had previously targeted prime minister Margaret Thatcher at the Conservative conference in Brighton in 1984. Five people were killed, including a Conservative MP.
A Downing Street spokesman declined immediate comment on today’s report.
On Tuesday, MI5 revealed that it had prevented nine terror attacks in the UK in the past year.
The country has also been victim to a number of successful attacks, including in March when Khalid Masood drove a car at pedestrians on Westminster Bridge and stabbed a policeman guarding Parliament. He killed five people in the attack.
In May, 22 people died when suicide bomber Salman Ramadan Abed targeted concert-goers at Manchester Arena and 11 people died when terrorists struck London Bridge in June. Later that month a man attempted to drive a van into a London mosque, during which a man died.
A subsequent vehicle attack took place on worshippers near the Finsbury Park mosque in north London while in September, an attempt to bomb a Tube train in London went wrong.
Also charges with terrorism offences today was Husnain Rashid, 31. He shared the address of Prince George's school with potential attackers as well as offering guides, tips, and suggested targets for attacks.
It is alleged Rashid from Nelson, Lancashire, shared a picture of Prince George and details of his school as well as a list of UK stadiums.
He is also accused of planning to travel to areas of Syria controlled by Islamic State to join the fighting.
Seperately, Mohammed Abdallah, from Manchester in northern England is charged over fleeing to Syria to join Isil. He is charged with possession of a firearm, receiving money for the purpose of terrorism, and belonging to a banned organisation. Abdallah was arrested at Heathrow Airport on September 23 last year after arriving in the UK on a flight from Tunisia. He is accused of traveling to Syria to join the Islamic State terror group in 2014.
Mohammed Abdallah, 26, from Moss Side in Manchester, is believed to have traveled to Syria with three friends in July 2014.
Abdallah's wheelchair-bound younger brother Abdalraouf, 24, who was unable to travel to the Middle East, stayed behind in Manchester to act as a facilitator and fundraiser for the group, the Old Bailey was told.
Abdalraouf was shot and paralysed while fighting alongside his brother in the Libyan uprising in 2011.
In another case a man was charged with terror offences after being arrested at Heathrow airport. Tadesse Kersmo, 51, appeared charged with eight counts of possessing articles likely to be useful to a person committing or preparing an act of terror, and one count of attending a place used for terrorist training. Kersmo was initially detained at Heathrow Airport after returning to the UK on January 4 this year.