Prime Minister Gordon Brown unveiled a memorial on Friday to a hero policeman who was killed on duty last year.

PC Jon Henry, who was stabbed in Luton town centre, was a former pupil at Bedford School.

Mr Brown joined PC Henry's wife Mary and his daughter Maggie at the ceremony.

Mr Brown told a crowd of about 150 in George Street, Luton, where the Bedfordshire policeman died: 'There is no man more courageous than the man we are remembering today who gave up his life in service.'

Chief Constable of Bedfordshire Police, Gillian Parker, said: "If it was difficult for us, how much more difficult was it for Mary, Jon's parents, his sisters, brother and other family and friends.

"Meeting them all hours after Jon had died, it struck me that despite their grief there was no anger at the police force. The message that came across that day was that Jon loved his job. I continue to admire your dignity from the start despite your deep loss."

The ceremony was the brainchild of the Police Memorial Trust, which was set up by film director Michael Winner, who said: "When you hear people say the police are never there, tell them about Jon Henry. He was there."

Jon's wife Mary said how she felt supported and drew strength from the number of cards, letters, flowers and gifts given by people who knew Jon and those who did not.

Last weekend Mary attended the annual National Police Memorial Day in Liverpool. She handed over, on behalf of the nation and officers everywhere, the scroll containing the list of fallen officers to event patron Prince Charles.

PC Henry had joined the force in Luton, his home town, where he had been born and raised. He was 36 years old.