It is impossible not to have mixed feelings at the convictions of Gary Dobson and David Norris for the murder of Stephen Lawrence 18 years ago

It is impossible not to have mixed feelings at the convictions of Gary Dobson and David Norris for the murder of Stephen Lawrence in the Eltham district of south-east London 18 years ago. Eighteen years ? the same span of years lived by Lawrence before his murder in 1993 ? is far too long for justice to be denied in any criminal case, let alone one that was so serious and so emblematic for the nation. Seven Scotland Yard investigations later, the police's efforts have finally generated two convictions by an Old Bailey jury. But it has been an insufferable ordeal for Lawrence's parents, both in terms of time and emotion. Doreen Lawrence, Stephen's mother, was right in every way to say that the verdicts are no cause for celebration.

This is true not least because the case is not yet over. Sentences have yet to be imposed on Dobson and Norris. There may be other charges to come, as Neville Lawrence, Stephen's father, urged after the verdicts. So the many failures to secure convictions over the long years cannot simply be dismissed now as an embarrassing prelude to yesterday's more satisfactory outcome that can somehow now be forgotten. These events have inflicted a generation of shame on the Metropolitan police and on those responsible for the delay of justice ? primarily the suspects and witnesses who lied for 18 years about that night and the friends and family who protected them.

It is important to state in plain terms why this was so. Stephen Lawrence was murdered because he was black. The initial police failure to follow the evidence trail with sufficient speed, professionalism and determination reflected exceptionally badly on some officers' values, and their understanding of the society they lived in. Racist attacks in Britain neither began nor ended with the Lawrence case. But the murder brought the question of police complacency about race ? supposedly a much higher priority in policing after the 1981 Scarman inquiry ? to a head. Much has changed for the better on that front since 1993, not least because of the Lawrence case and, in particular, because of the 1999 Macpherson inquiry. Yesterday's convictions were the result of the indignation which engulfed the police for their earlier failures.

The turning of the tide on the Lawrence case clearly owes more to Stephen Lawrence's parents than to anyone else. Their reactions to yesterday's result differed ? Mrs Lawrence less reconciled, her former husband more relieved. Yet their common determination to win justice for their murdered son was the key, assisted, it should be said, by bold journalism from the Daily Mail. It did not simply keep the case in the public eye. It also became a national reprimand to the criminal justice and political system in a wider sense. Changes were made ? improvements in forensic investigation of the sort which delivered the crucial evidence at the trial, as well as legal changes allowing the double jeopardy rule to be set aside and permitting evidence of bad previous character to be heard in court. The verdicts vindicate those changes. There is less justification for any complacency over the Lawrence case outcome than in most criminal cases. The verdicts have not purged English criminal justice of its failures. Hate crimes still go unprosecuted. But Neville Lawrence was right to say that he has spent the past seven weeks at the central criminal court watching justice being done; right, too, to speak of relief at the outcome. In the end, good policing, official determination and a jury have proved that the system is strong enough to correct its mistakes. The convictions of Dobson and Norris are a far better outcome for the Lawrences and for Britain than their acquittal would have been. Mixed feelings? Of course. Profoundly so. But as Shakespeare puts it at the end of the convulsions of All's Well That Ends Well: "All yet seems well; and if it end so meet the bitter past, more welcome is the sweet."