By Clare Babbidge BBC News

As four men face jail terms for killing policewoman Sharon Beshenivsky, many officers say they are facing increasing danger on the streets.

These guns were taken off the streets of Manchester recently

Pc Beshenivsky, 38, was shot during a robbery at a travel agents in Bradford, West Yorkshire, in November 2005.

The mother-of-three died after a round missed the bullet-proof part of her body armour.

Yusuf Abdillh Jamma has been found guilty of murdering Pc Beshenivsky, while Muzzaker Imtiaz Shah earlier admitted to her murder.

Brothers Faisal and Hassan Razzaq were cleared of murder but found guilty of her manslaughter.

Pc Beshenivsky's friend and colleague, Pc Teresa Milburn, was injured in the same robbery.

Research carried out by the Police Federation for England and Wales earlier this year found 40,000 officers had been faced with a knife and 7,000 threatened with a gun during the last two years.

Paul Tonks, chairman of the West Midlands Police Federation, said during his 28 years' service there had "always been" colleagues injured but the job had become more dangerous recently.

MEMORIAL ROLL INCLUDES: 1994 - Pc Lewis Fulton. Knifed while responding to a 999 call in Glasgow 1997 - Pc Nina Mackay. Stabbed to death in Stratford, east London 1999 - Pc Raja Ahmed. Killed by car thief in Manchester 2001 - Pc Alison Armitage. Run over by a car thief in Oldham, Greater Manchester 2003 - Pc Stephen Oake. Died of stab wounds during an anti-terror raid in Manchester 2003 - Pc Ian Broadhurst. Shot after stopping a motorist in Leeds on Boxing Day

He said: "The easiest way to show this is that now officers wear a stab and ballistic-proof vest and are issued with a CS incapacity spray.

"They are also issued with a baton which is far more effective than those issued 28 years ago."

One of Pc Tonks' colleagues was shot and injured in Wolverhampton in November 2006. Two years ago another West Midlands officer, Detective Constable Michael Swindells, was stabbed to death.

Knife threat

Pc Tonks' concerns over safety are echoed throughout the police service. Pc Tonks said the carrying of guns and knives was a "worrying trend".

He expressed concern at the amount of firearms in circulation and the "ease with which they can be obtained".

But he added: "Firearms have been used against police, but it's still extremely unusual."

The latest crime figures included a 10% rise in robberies at gunpoint.

'Very violent'

Pc Norman Brennan said violent crime had "shot through the roof" during his 27 years with the Metropolitan Police.

Pc Brennan, who founded the pressure group Protect the Protectors, said: "Britain is very violent and the increasing violence against police mirrors that faced by other people in society."

The increasing violence against police mirrors that faced by other people in society Pc Norman Brennan Protect the Protectors

He said: "I have taken on people with knives at least three times and one time I got stabbed in the chest, which nearly cost my life. It had a devastating impact."

When he was stabbed in 1985, he had only been back at work for five weeks after more than a year off recovering from another traumatic attack.

Pc Brennan said the number of firearms offences committed each week had gone up from "just a handful" 30 years ago, to more than 230. He said some gangs were using Kalashnikov rifles and machine pistols able to fire 40 or 50 bullets in rapid succession.

Home Office figures showed 17,525 people were found guilty or cautioned for "assault on a constable" in England and Wales in 2004 - over 5,000 more than 10 years earlier.

A survey by Jane's Police Review in March found 21,845 assaults on officers in 51 forces across the UK last year. Most forces showed year-on-year increases, but one in three forces recorded a fall.

Deaths on duty

Despite this apparent rise in danger, the number of police officers killed on duty as a result of criminal acts in Britain has not risen sharply.

Police Memorial Trust figures show 27 officers were killed in the 1970s, 42 in the 1980s, 21 in the 1990s and 15 since 2000.

Those figures do not include police officers killed in Northern Ireland.

The trust, which erects memorials to officers killed on duty, was set up by film producer Michael Winner after the death of policewoman Yvonne Fletcher in 1984.

But were things really much safer in his day?

Mr Winner is a vocal advocate of arming police officers, a view shared by Pc Brennan, who said it was only due to "wonderful advances in medical science" that more police officers in Britain had not died from their injuries.

But the Police Federation said its most recent survey suggested 77% of officers rejected the arming of frontline officers.

Pc Brennan, who drives a 999 response car, said increasing attacks meant police morale was low and they felt they were not fully supported by the public and "contemptuous sentences" for police assaults.