Ten years after the event, Queenie Fletcher sits watching footage of her daughter, Yvonne's, death, her distress tightly controlled. It is the first time that she has faced the images of the shooting of the young policewoman which were once so familiar to everybody else in the country.

Most people still know Yvonne Fletcher's name, even if they are not sure why. She was shot while policing a demonstration of Libyan dissidents outside the Libyan People's Bureau in London, yards away from her fiance, Michael, a fellow constable. As she lay dying, her mother was shopping in Salisbury, totally unaware. The first sign of trouble was a police poster outside Debenham's with Mrs Fletcher's name on it. She and her husband, Tim, were rushed to London, but Yvonne died an hour after the shooting.

After an 11-day siege, her killers were permitted to fly back to Libya with the rest of the bureau's occupants, protected by diplomatic immunity.

Yvonne's death marked a turning point in relations between Libya and Britain. Diplomatic links were severed and public opinion of the Gaddafi regime crystallised into a highly emotional national outrage.

For Yvonne's family, trying to come to terms with their grief, the fact that her murder was so public and had such far- reaching repercussions added an extra dimension of difficulty: 'It was headlines for so long, that was the trouble,' says Mrs Fletcher. 'It's not as if it happened and then in a month's time it was all forgotten - it just went on and on. I think that made it more difficult. When we went out I felt that people I didn't know were looking at me, and thinking is she that woman . . .?'

The public profile forced on Queenie Fletcher - meeting Margaret Thatcher when she unveiled the memorial plaque to Yvonne 10 months after her death, for example - was, she now thinks, a blessing in disguise: 'Those occasions help you to cope because you've got to be strong.'

Mrs Fletcher is a great believer in putting on a brave face and keeping busy. It's a rather discredited method of dealing with grief these days, but it helped: 'Perhaps it's easier in a village because everybody knows you. Talking to other people about Yvonne helped. And I think it was important that I didn't give up things like the WI, even though I didn't feel like making the effort, because it was something else to think about, not just myself. Talking to different people made me think life's got to go on.'

But the driving forces behind Mrs Fletcher's determination to keep going were her two daughters, Sarah, who was 18 within days of Yvonne's death, and taking A-levels, and Heather, then 22, about to take her nursing finals: 'That was all very important. It wasn't fair to let Yvonne dominate because the girls had got all their lives in front of them and they had to get on with what they wanted to do. Because Yvonne had done what she always wanted to do, since the age of three. She loved being a policewoman; it was her life.'

Although her parents insisted that at 5ft 2in she was too short to join the police, she wrote to a dozen forces before being accepted by the Metropolitan Police. Her job didn't worry her mother: 'Yvonne always said you could walk out into the road and get knocked down and killed. She didn't think of her life being in danger. All mums worry, but I didn't worry unduly. It was what Yvonne wanted to do and that was it.'

Had Yvonne's killers been dealt with at the time, life would have turned out very differently for the Fletchers. 'Until they find the killer, nothing's going to be resolved. What happened in St James's Square is always going to be brought up. And whenever it is, I can guarantee my telephone will ring. That is painful - I think: Oh gosh, I've got to go through all that again. If we knew Yvonne's killer was in prison, the whole thing would be finished and life could go on.'

Mrs Fletcher's desire to find out who killed her daughter has been given a new impetus by her five grandchildren, all born since Yvonne's death. They ask about their aunt; their grandmother wants to be able to tell them more than the bare facts.

So, when Channel 4 asked her to take part in making a documentary about relations between Libya and Britain since Yvonne's death, she agreed. There was no question of dredging up painful memories, since the memories had never had a chance to fade.

Last month Mrs Fletcher went to Libya, met Muammar Gaddafi and government ministers and addressed a rally, which was televised there. It was a journey that demanded physical bravery and moral gumption from a 61-year-old woman who had lived in the same Dorset village for 30 years and had never been abroad.

The response from the ordinary citizens of Tripoli was the chief satisfaction of the trip, and it transformed her opinion of Libya. 'You would think they would hate the British but they don't. People would tell me how sorry they were about Yvonne's death, that it shouldn't have happened.'

Colonel Gaddafi was less forthcoming. Mrs Fletcher finally met him at a rally after waiting for several days: 'It was a relief that we were actually going to do something, but the rally was terrifying. Before I went to Libya I thought of Gaddafi as quite a frightening man. But he seemed quite frightened himself, and very ordinary. He said how sorry he was about Yvonne and I said how sorry I was that he had lost his daughter in the US raid on Tripoli.'

Mrs Fletcher has reached her own conclusions about why the British government seems reluctant to talk about Yvonne's death, and why she has heard nothing from the Foreign Office for 10 years: 'I think the Government probably knew more about that demonstration than anyone admits, they knew that there was something different about it, but the message wasn't passed on. It should have been policed differently and constables like Yvonne should not have been there.'

Although Mrs Fletcher came back from Libya with more questions than answers, she is not disappointed. 'I had hoped we would be able to find out something but in my heart I knew it would be difficult. I don't know if the trip made me feel better, but it hasn't made me feel any worse.'

In the meantime, she makes do with the half apology received from Gaddafi. As she says, it's better than nothing.

'Frontline', Channel 4, Wednesday 9pm.

(Photograph omitted)