The final member of the "Oval Four" - four young black men who were "fitted up" by a corrupt police officer nearly 50 years ago - has finally had his conviction overturned by senior judges.

Winston Trew, of Lewisham, Sterling Christie, George Griffiths and Constantine "Omar" Boucher - then aged between 19 and 23 - were arrested at Oval Underground station in 1972 by a police unit known as "the mugging squad", who accused them of stealing handbags.

The unit was run by Detective Sergeant Derek Ridgewell, who had previously served in the South Rhodesian (now Zimbabwean) police force, and was involved in a number of high-profile and controversial cases in the early 1970s.

The Oval Four were convicted in November 1972 of attempted theft and assaulting police, and Mr Christie was also found guilty of theft of a handbag, following a five-week trial at the Old Bailey.

All four were sentenced to two years, later reduced to eight months on appeal.

Mr Trew, now 69, Mr Christie, now 70, and Mr Griffiths, now 67, had their convictions overturned by the Court of Appeal in December, after a referral by the Criminal Cases Review Commission (CCRC) earlier in 2019.

Mr Boucher's conviction was not referred to the Court of Appeal, as the CCRC had been unable to trace him - but Mr Boucher, now 71, contacted them shortly after his friends' convictions were overturned.

At a short hearing in London on Tuesday, Lord Justice Fulford - sitting with Mrs Justice Carr and Mr Justice Goss - quashed Mr Boucher's conviction, saying that the safety of the conviction was "fundamentally undermined by the apparent lack of integrity of DS Ridgewell and the team he led".

Lord Justice Fulford added: "It is clear that Mr Boucher's conviction is unsafe. It is highly unfortunate that it has taken nearly 50 years to rectify this injustice."

In a statement after the hearing, Mr Boucher's solicitor Jenny Wiltshire, head of serious and general crime at Hickman & Rose - who also represented Mr Trew and Mr Christie - said: "While it is, of course, happy news that Mr Boucher's conviction has been quashed, the fact that it has taken nearly so long is very concerning.

"The British Transport Police and the Home Office have known about this officer's corruption for decades. Yet they have done little to right his wrongs.

"DS Ridgewell was first denounced as corrupt in 1973. He was imprisoned in 1980. The BTP could have re-examined his cases then. But they didn't.

"They instead left it to his victims to try and work out for themselves exactly how they had been set up, and to gather the evidence they needed to prove their innocence.

"In my view, the BTP should now conduct a wholesale review of all this officer's cases. It seems to me very likely that there may be many other victims of his corruption."

Ridgewell was involved in a series of controversial cases in the early 1970s in which young black men were falsely accused of crimes - which led to calls for the Home Secretary to open an inquiry - culminating in the 1973 acquittals of the "Tottenham Court Road Two", two young Jesuits studying at Oxford University.

He was then moved into a department investigating mailbag theft, where he joined up with two criminals with whom he split the profits of stolen mailbags.

Ridgewell was eventually caught and jailed for seven years, dying of a heart attack in prison in 1982 at the age of 37.

In January 2018, Stephen Simmons' 1976 conviction for stealing mailbags was quashed after he discovered Ridgewell was later jailed for a similar offence just two years after his own conviction.

Part of the evidence in Mr Simmons' appeal was Mr Trew's book Black for a Cause... Not Just Because...' which detailed Ridgewell's long history of "fit-ups".

At the hearing in December, Judy Khan QC said Mr Trew, Mr Christie and Mr Griffiths' case was "perhaps unprecedented" in that it had "already been cited in support of quashing another appellant's conviction" before their names had been officially cleared.