There was no wall of silence after the murder of Stephen Lawrence. In the first hours and days, witnesses came forward or left notes with names of members of a notorious gang which they identified as being involved in the black teenager's death. But nobody was arrested for two weeks. This delay was highlighted as the "fundamental" error which has ensured that 19 years on, the Metropolitan Police is still having to deal with the legacy of that original, bungled investigation.

That two-week gap potentially allowed suspects to dispose of incriminating evidence and organise their stories. It contributed to the fact that, until January 2012, nobody was convicted for a murder that was played out under lights on a busy road of a capital city. There is no guarantee that had police moved earlier they would have secured convictions. But they didn't.

Along with the incompetence and institutionalised racism identified by the Macpherson report, the Lawrence family has long maintained that police corruption played its part. Despite their beliefs, that has not been confirmed by any of the inquiry reports that have followed.

There is little doubt that the Metropolitan Police has changed. The force has spent millions and employed its best detectives on a case that finally resulted in the conviction of two men this year. The new Commissioner, Bernard Hogan-Howe, acted swiftly following the latest allegations of racism in the force, recognising the toxic legacy of the failed Lawrence investigation. Officers have reported allegedly racist comments made by their own colleagues.

When The Independent this year published previously unseen details from intelligence files on an allegedly corrupt detective on the original inquiry and following other reports, Scotland Yard began an inquiry, trawling thousands of documents and interviewing former officers to try to put the issue to bed, one way or another.

The conclusion of its report – and one by the police watchdog – was that there was no new evidence or allegations that merited further investigation. Yesterday, the Home Secretary – lobbied by Doreen Lawrence – thought otherwise and called for a new review to be led by Mark Ellison, QC.

The review is testament to the tenacity of Mrs Lawrence but also the continued hold that the case has over public consciousness. Whether it answers the family's questions remains to be seen.