Mrs Lawrence ... 15 years on

It was on this day in 1993 that Stephen, 18, was stabbed to death by a gang of white youths in Eltham. His killers are still at large.

Today, hundreds of people gathered at St Martin-in-the-Fields Church in Trafalgar Square for a memorial service led by the Archbishop of Canterbury. The Lawrence family was joined by friends, politicians, police officers and community leaders from across Britain.

Before the service Mrs Lawrence, 56, laid a bunch of roses at the place of his death, as she has every year. She said: "Stephen is always, always, in my heart, and today of course, 15 years on, I am just thinking about the waste of his life."

Later, at the church, she added: "For me and Stephen's family, the pain of our loss remains undiminished. Today's service offers us and others an opportunity to mark his life and to remember the wonderful son, brother and friend who brought joy to so many lives."

Mrs Lawrence and her former husband Neville were awarded OBEs in 2002 in recognition of their work for the community. They fought a long campaign to expose failings at the heart of the Metropolitan police.

The Macpherson report, published in the wake of Stephen's death, branded the police "institutionally racist" and led to wholesale changes in policing and race relations.

Mrs Lawrence added: "Much has changed in the last 15 years and it is some comfort that out of such tragedy has come great improvements in the way the police and other organisations deal with race and diversity issues."

Stephen, an A-level student who hoped to be an architect, was with his friend Duwayne Brooks when they were attacked at a bus stop in Well Hall Road by a gang of white youths who shouted racist abuse at them.

Stephen was stabbed in the neck and staggered 250 yards before collapsing. No one was convicted but five men were arrested soon afterwards - Gary Dobson, Neil Acourt, Luke Knight, Jamie Acourt and David Norris.

The Crown Prosecution Service said there was insufficient evidence to prosecute any one for murder in 1994, and again in 2004. Dobson, Knight and Neil Acourt were acquitted of murder after a private prosecution by the Lawrences collapsed at the Old Bailey in 1996.

Last November, Scotland Yard confirmed it was investigating new forensic evidence. Following the abolition of the double jeopardy rule two years ago, the men could face another trial.