Police in London have defended their handling of violent clashes with students, during which protestors attacked a car carrying Prince Charles and his wife, Camilla.
Demonstrators against the Government's trebling of university fees surrounded the royal vehicle, some shouting off with their heads.
More than 50 people were injured in clashes in the city.
Prince Charles and the Duchess of Cornwall were on their way to attend the Royal Variety Performance and as usual were travelling with their security detail and police outriders.
The couple were unhurt. They attended the event at the London Palladium as scheduled, but later left the theatre in a police van.
The Metropolitan Police Commissioner, Sir Paul Stephenson, says there had been reconnaissance of the route the car took, but the movement through London of thugs had been unpredictable.
He said the police response was a measured one.
Prime Minister David Cameron said the attack was shocking and regrettable and those who provoked the violence will face the full force of the law.
He said the lapse in protection is worrying, but he blamed the protestors, not the police.
Prince Charles said he totally understood the difficulties police faced.