By Press Association

DAVID Cameron made his first public engagement since retiring as Prime Minister at a memorial event honouring Sale police officer Fiona Bone, and her colleague Nicola Hughes, who were murdered in a gun and grenade attack.

Mr Cameron, who on Wednesday said that serving as the country's Prime Minister had been "the greatest honour" of his life, attended the Police Memorial Trust's service for Pc Bone, 32, and Pc Hughes, 23.

The two officers were killed by wanted one-eyed gangster Dale Cregan in September 2012 after being lured to their deaths by the criminal following a bogus 999 burglary call to a house in Hattersley, Greater Manchester.

At the ceremony, Mr Cameron unveiled a memorial stone in their honour at The Hub in Mottram, Tameside, close to where the two officers fell, to serve as a reminder of the officers' sacrifice.

Mr Cameron addressed the police officers' families, colleagues and dignitaries to tell them that it was "vital" that heroes like Pc Bone and Pc Hughes were honoured like this.

He said: "I spoke last night outside Number 10 Downing Street for the last time and I spoke about the extraordinary ethic of service in our country particularly our police, our intelligence, our armed forces. And so it feels appropriate that while I am no longer Prime Minister, the new Prime Minister asked me to carry out this event and I'm so delighted to do that on her behalf.

"Come hell or high water we know the police are there for us."

Mr Cameron said that it was a day to give thanks to the policemen and women who serve the country whilst retelling Pc Bone and Pc Hughes's story.

Cregan, who is serving life behind bars, had been on the run and was wanted for killing David Short, 46, and gunning down his son, Mark Short, 23, in Droylsden.

Mr Cameron said that the officers' murder had been "an act of pure evil" adding that it "shook the policing family to its very core".

He added: "Our fallen heroes in the police exemplify the very best of us. To me they are the very epitome of service, bravery and sacrifice.

"This monument will ensure that their stories live on."

He added: "Fiona and Nicola are lights that will never go out. We are grateful of the service that they gave to the community. We will never let them be forgotten. We are so proud of them. May they rest in peace."

Pc Bone and Pc Hughes are the 46th and 47th officers killed in the course of duty that have been honoured by the Police Memorial Trust since its formation in 1984.

The Trust was founded by the late Michael Winner whose widow Geraldine took on chairmanship after her husband's death.

Mr Cameron said: "On behalf over everyone here, including the Hughes and Bone families, their loved ones, their friends and colleagues, I want to thank for all the work you do, Geraldine, in chairing this important charity and taking forward all of Michael's fantastic work in setting this up.

"It is said that the character of a country is revealed not only in the men and women it produces, but by those we choose to remember - the lights that we decide should never go out. The stories that we keep alive so that future generations may one day hear them, and our fallen heroes in the police exemplify the very best of us."

Mr Cameron added that the officers were there for the people of Mottram doing an "outstanding job" and had shown "unbelievable courage" on the day of their murder.

Pc Bone was shot at 22 times but did not leave her colleague Pc Hughes who was lying injured.

The pair had been described as forming a "compassionate partnership who had wanted to make a difference".

Mr Cameron added: "That day they made the ultimate sacrifice, they were murdered so callously, heinous, monstrous and despicable, even these words can't describe the horror of what was done."

Ian Hopkins, Chief Constable of Greater Manchester Police, said that it was an important day for the officers' families, colleagues and for the community.

He said: "This sends out a real message about policing in this country and that we do it with the consent of the people that we serve and on the main we do it as unarmed officers and sadly sometimes officers give the ultimate sacrifice and lose their lives in the line of duty.

"The families feel hugely honoured that this is happening today. They think this is a really fitting tribute."