Picture taken outside Lion and Lamb pub Hoxton on 16 May. Left to right are:Denis Cohen (Sam's cousein), Paul May, Wendy Cohen,Sam Hallam, Jacky Westbrook (Sam's aunt), Keely Cohen (Sam's cousin) Trevor Hallam (Sam's uncle), Sarah (Sam's cousin don't know surname), Charlotte Cohen (Sam's cousin) and Daisy Hallam (Sam's sister)

Lead campaigner Paul May has spoken of Sam Hallam’s distress to realise a month after his dad’s death that a photo of his late father taken on the night of Kassahun’s fatal attack was crucial to his appeal.

In November 2010 Thames Valley Police came to Bullingdon prison to show Sam and Paul the photos taken on Sam’s phone, which had been seized by Met police when he was arrested six years previously and not investigated.

They revealed that contrary to Sam’s belief that he had been with his friend playing football, he had actually been with his father Terry in the George and Vulture pub in Pitfield Street when the attack on Essayas Kassahun took place.

Sam’s father had killed himself just a month before Sam saw the photo, because of the stress of his son’s incarceration.

“It was a physical shock to Sam to be shown a photo of his late dad,” said May.

“It was very distressing, not long after Terry’s funeral to be shown that, and to realise this photo was crucially important.

“The court of appeal accepted as much that this was a really important photo, it placed Sam 1.7 miles from the scene of the murder, shortly before the murder.

“When I came out of the interview, my wife picked me up in the car, and I immediately blacked out, I found out the next day that’s what Sam did as well, it was that intense, it was about his whole future and whether he was going to have a future.

“We also had evidence he had been in the pub, as one of the suspects said he had been there and seen Sam as he was on his way back from the murder scene,” added May.

Sam always maintained he was sure there were photos taken on the night of the murder which would show he was with his friend Timmy Harrington who he was playing football with.

But back in 2004 Harrington told police he hadn’t seen Hallam at all that week, and although he was much less sure in court, the prosecution claimed in the 2005 court case that Sam had concocted a false alibi.

The photos taken of Harrington on the phone proved Sam had met with him that week, but the night after the murder - but this only emerged in 2010 when Thames Valley Police reopened the investigation at the Criminal Cases Review Commission’s (CCRC) request.

Paul May also criticised the Met for never carrying out “cell site analysis” on Sam’s mobile phone to find out which phone mast he was nearest at the time of the attack.

In fact, Sam Hallam had been nowhere near the scene of the crime, people at the scene said he was not there, he was not captured on CCTV and there was no evidence linking him to the attack on Essayas Kassahun and his friend, Louis Colley.

So just how was he found guilty?

The Crown Prosecution Service’s case was mainly based on evidence from two witnesses who said they were present at the murder scene and that they had seen Sam Hallam take part in the fatal attack.

At the jury trial in 2005 the first witness, Phoebe Henville, said she had seen Sam Hallam among the group of youths who carried out the attack.

But she changed her story several times to police and in court.

Henville did not personally know Hallam, but heard “rumours” a “Sam” was involved, and after coincidentally bumping into Hallam in the street, she claimed he was one of the killers.

The second witness, Bilel Khelfa, told police he had seen Hallam standing over Kassahun, wielding a baseball bat with a screw protruding from its end.

But he retracted this in court, saying he only named Hallam because he had been told by Henville he was involved.

Subsequently the Thames Valley investigation on behalf of the CCRC revealed the ‘Sam’ mentioned by the witnesses was another Sam, not Mr Hallam, whose identity was ‘called in’ by a local man.

This lead was never followed up by the Met, and the message was never disclosed to Hallam’s lawyers.

As part of the CCRC inquiry, Thames Valley officers interviewed several new witnesses who came forward to say Mr Hallam was not involved.