A roller-skater sparked panic after he almost collided with a car carrying the King to Westminster Hall.
The drama unfolded as Charles made his way to perform a vigil beside the Queen’s coffin on Friday evening.
Footage shared online showed a man on roller-skates speeding towards the royal cavalcade near Parliament Square in London before being floored by up to eight police officers.
He was handcuffed at the scene before officers established that he had no malicious intent and let him go.
A spokesperson for the Metropolitan Police said: “At approximately 7.40pm, as police vehicles were entering Parliament Square, a pedestrian attempted to cross the road.
“An officer on foot quickly intervened, bringing the man to the ground in order to stop him from continuing. The man was subsequently spoken to by officers before being let on his way.”
The incident came minutes before the King and his siblings stood silently guarding their mother’s coffin in Westminster Hall in a ceremonial event known as the Vigil of the Princes.
Charles, Prince Andrew, Princess Anne and Prince Edward took part in the 10-minute tradition, which was first established when King Edward VIII died in 1936.
All four royals were dressed in military uniform, including Andrew, who has been barred from such dress since being relieved of his royal duties. An exception was made as a "special mark of respect" to the Queen, Buckingham Palace said.
Other members of the Royal Family, including Camilla, the Queen Consort, Vice Admiral Sir Tim Laurence and Sophie Wessex, along with some of the Queen’s grandchildren, were also present.
The Queen’s eight grandchildren, including Princes William and Harry, will hold another vigil in the hall on Saturday.
