The murder of Stephen Lawrence and the subsequent police investigation were a devastating tragedy for the 18-year old's family and a metaphor for the racism that polluted British society in the early 1990s.

The conviction, finally, of Gary Dobson and David Norris yesterday for this callous crime may bring some comfort to Doreen and Neville Lawrence and help lift a vile stain from the reputation of the Metropolitan Police. And yet, on both counts, this is unfinished business.

Stephen was not the first upstanding young black man to be murdered by white thugs in cold blood, nor the last. What marked this case out was the determination of his parents, especially his impressive mother, to fight for justice and refuse to be fobbed off with second-class treatment because of the colour of their skin.

More than a score of potential witnesses named the likely perpetrators but a plodding investigation marked by monumental incompetence, plus an unwillingness to accept such murders were racially motivated, resulted in nobody being charged. An attempted private prosecution of three of the suspects failed for want of evidence.

The Lawrence family's persistence won them an inquiry and it was a good one. Sir William Macpherson made 70 recommendations and branded the Met as not only incompetent but also institutionally racist. The Macpherson report was a wake-up call, not just for the police but a whole society degraded by casual racism. The treatment of black footballers was but one example.

The result was a paradigm shift in tone, not only in the Met, or the British police in general, but society as a whole. Changed attitudes to racism in sport are testament to that revolution. And yet.

As Doreen Lawrence observed yesterday, racism has not disappeared. It is simply less overt. Black people still have a different experience of policing. There are still far too few black police officers and black youths are more, not less, likely to be stopped and searched than in 1999.

The other lesson of this case is that we should never give up on the quest for justice. Lord Macpherson's remarkable foresight in suggesting a review of the law on double jeopardy, the decision to invest considerable resources in a cold case review, plus impressive advances in forensic techniques, enabled Dobson and Norris to be brought to justice. But Stephen Lawrence was murdered by five or six racist youths, not two. The fight must go on to put the others behind bars too. This is not the end of this case, any more than it is the end of racism.