The murder of Sgt Derek Robertson, 39, who was married with children aged seven and four, was the second of a Metropolitan Police officer on duty in five months. Last October Constable Patrick Dunne, 45, was shot dead in Clapham, south-west London.
The latest killing has intensified the debate about issuing police with body armour and firearms. It is also likely to increase support in the House of Commons for an amendment which has been tabled to the Criminal Justice and Public Order Bill, calling for the restoration of the death penalty for the murder of police officers.
Last night, detectives investigating the death of Sgt Robertson were interviewing three men. Two were arrested at the scene and the third a short time later.
Police said the incident began when the wife of a sub-postmaster at New Addington telephoned her husband at work early yesterday morning. The tone of his voice made her suspicious; he agreed when she asked whether she should call the police.
A radio alert was issued, saying there were 'suspicious circumstances' at the sub-post office and Sgt Robertson, on the early morning patrol shift at South Norwood station, responded. He arrived at the same time as other officers and immediately went to an alleyway at the side of the building where he saw three men escaping. He tackled them and was stabbed in the ensuing struggle.
A medical team from the Royal London Hospital arrived by helicopter and performed open heart surgery at the scene. The officer was flown to the hospital, where he was later pronounced dead.
Paul Condon, the Commissioner of the Metropolitan Police, said the death was 'tragic'. Sgt Robertson, who joined the Metropolitan Police in 1973 and had been at South Norwood for three years. He was an ordinary officer who had paid the 'ultimate sacrifice'. Colleagues described him as 'a lovely man, popular and well respected'.
Sgt Robertson appeared to have decided to go to the scene rather than return to his station to collect body armour. The 28,000-strong force has about 4,000 anti-ballistic and stab-proof vests; although most are issued to specialist squads, between five and ten vests are available at each divisional station or carried in its fast response cars. Most are heavy-duty vests for wearing above clothes.
About 600 are a dual purpose type which can be worn under clothes but are still considered too heavy to be worn permanently. The vest is similar to that developed for Northumbria police following the stabbing to death of a sergeant last year. Mr Condon said yesterday if there was a suitable, lightweight, bullet and knife proof vest available, he would purchase it immediately for all officers.
Mike Bennett, chairman of the Metropolitan Police Federation, predicted an increase in calls for officers to be armed. 'I have slowly come around to the view that this is now the only option. The people who are out there putting themselves at risk say they want to carry arms.'
He said the Government had become too concerned about the image of the police. 'We need to say 'stuff the image' and make sure that our people are properly protected. You can't wear body armour all the time and if someone comes at you with a knife, you may not be able to get your baton out in time. Firearms are the only sure defence,' he said.