London: A shocking picture of the police blunders that caused a London teenager to spend nearly eight years wrongfully imprisoned for murder was revealed on Saturday for the first time.

Sam Hallam, just 17 at the time of his arrest in 2004, was freed on Wednesday by the Court of Appeal after it heard fresh evidence which demolished every aspect of the prosecution case.

In an interview on Saturday, Hallam also revealed that the police officer in charge of his botched case, Mick Broster, was the same detective whose subsequent investigation into the mysterious death of "body in the bag" MI6 agent Gareth Williams was strongly criticised by a coroner earlier this month.

Hallam, now 24, said: "When I was first arrested, I assumed I'd be home in a day or two, because I had faith in the system, and they had no credible evidence.

"Instead I went to prison and lost my youth, all because of the mistakes and errors made by the police and the courts. "They had the evidence all along that proved I wasn't lying.

"The Met must think Mick Broster is doing something right, because they promoted him, but he's not. Although the Williams case was also really important, he just went on making mistakes. There seems to be a pattern here.

"I'm not surprised he botched the ‘body in the bag' spy case. He's the one who stole eight years of my life for a murder I couldn't have done."

Hallam was convicted on the strength of flimsy witness statements, amongst other weak evidence.

A Metropolitan Police spokesman said the force had nothing to add to a statement issued on Thursday, in which it expressed "regret: that Hallam had been wrongly imprisoned.