The heir to the throne and his wife Camilla's limousine came under attack as it drove through a demonstration against student tuition fees earlier this month.
Their Rolls-Royce was surrounded by a mob who smashed a rear window, splattered it with paint and tried to overturn it as the couple traveled to the Royal Variety Performance in the capital's West End.
However according to Daily Mail, a police sergeant told a member of the prince's protection team that the area should be avoided as 200 violent protesters descended on the busy shopping street.
But the advice, which was logged in official police records, was ignored and the limousine was driven right through the center of the protest.
A Scotland Yard report written by Met Commander Ian Quinton has now been handed to Home Secretary Theresa May detailing what went wrong on December 9 in what has been billed as one of the biggest lapses in royal security for years.
A source said of the file, which is unlikely to be made public: "If the Quinton report was ever published, it would make extremely uncomfortable reading."
At one point, Camilla - who was jabbed in the ribs through the car window by a protestor - was reportedly so afraid she was reduced to tears and was seen grabbing Charles' hand inside the armored vehicle.
Charles, 62, and Camilla, 63, eventually arrived at the theatre unharmed.
Prime Minister David Cameron afterwards condemned the attack as "shocking and regrettable" and said the protesters would "face the full force of the law".
