No officers will face disciplinary action after a mob attacked the Prince of Wales and the Duchess of Cornwall during the tuition fees protests, Scotland Yard said.
Metropolitan Police Commissioner Sir Paul Stephenson ordered an internal review of the incident, which was submitted to Home Secretary Theresa May, after the Duchess was poked in the ribs with a stick as the royal car was attacked in London's West End.
Scotland Yard said no officers would face disciplinary action after it was reported that royal protection officers were warned by a police colleague not to drive down Regent Street 15 minutes before the royal couple were attacked by the mob on December 10.
A police sergeant told a member of the couple's protection team that the area surrounding the road should be avoided because up to 200 thugs were in close proximity, the Daily Mail said.
But the advice, which was logged in official police records, was not followed and the couple's royal limousine was driven straight into the area where the protesters were, the newspaper reported.
The royal couple were travelling to the Royal Variety Performance when they were caught up in violence surrounding the vote on tuition fees.
The Duchess was pictured looking shocked and distressed and they were forced to leave afterwards in the back of a police van.
Royal security was expected to be stepped up in the wake of the review.
The Prince has already been seen using an armoured Bentley with extra bodyguards supported by a carrier of police officers.
Sir Paul, who has previously suggested it was unlikely anyone would lose their job over the embarrassing episode, including head of royal protection Commander Peter Loughborough, has praised officers for their "enormous restraint" during the incident, suggesting members of the rioting mob were lucky not to be shot.