The police’s response to the mayhem caused by student riots yesterday was an “embarrassment” a Police chief admitted last night.

In a public apology, the Metropolitan Police Commissioner Sir Paul Stephenson admitted: “We didn’t expect this level of violence,” after hundreds of students stormed Conservative party headquarters at Millbank Tower causing £1million worth of damage.

Despite knowing in advance that thousands of student protesters were expected to converge on Millbank, only 225 officers were put on duty.

Police looked on helplessly as protesters used chairs and fire extinguishers to smash through Millbank’s entrance lobby before occupying the roof of the building.

The march left 10 people in hospital and led to 35 arrests.

Sir Paul Stephenson said: “It’s not acceptable. It’s an embarrassment for London and for us. I am determined to have a thorough investigation into this matter.”