Charlie Gilmour says he wants to say sorry for the "terrible insult" to the thousands who died for the country. He says he did not realize the Cenotaph in central London commemorates Britain's war dead.
He added in a statement Friday that he was ashamed for his "moment of idiocy."
Gilmour was among thousands of students and youths protesting in the streets of London on Thursday. The protests turned violent when some threw objects at police.