A former sub-postmaster serving life in prison for murdering his wife is seeking a fresh appeal of his conviction, arguing the Post Office Inquiry has shed new light on his case.

Robin Garbutt was found guilty in 2011 of murdering his wife Diana at their home in North Yorkshire the previous year, but has always maintained his innocence.

Evidence from the Horizon IT system and the Post Office helped convict him after prosecutors said he had been stealing money from his branch, faked a robbery and killed Diana to cover it up.

Garbutt’s lawyers have applied to the Criminal Cases Review Commission to have it sent back to the Court of Appeal. Former Post Office Minister Kevin Hollinrake MP told the BBC he was backing a fresh review.

Garbutt’s wife Diana was found dead in their flat above the post office they ran together in the village of Melsonby in North Yorkshire in 2010. She’d been attacked over the head with a metal bar in her bed.

Garbutt claimed they were the victim of an armed robbery.

He told police a man forced him to open his Post Office safe at gunpoint and hand over £16,000 before he was able to run upstairs where he discovered his wife’s body.

But the jury didn’t believe him. The prosecution said he had staged the robbery and had been stealing money from his branch, and then killed Diana to cover it up, fearing he was about to be discovered. They claimed he was in financial difficulty and their relationship also had problems.

There was no physical evidence linking him to the murder. A key plank of the case against him was based on data from the Horizon system and how it was interpreted by the Post Office.

Unlike the familiar tales from hundreds of other sub-postmasters, this one isn’t about shortfalls in branch accounts.

The prosecution claimed Garbutt was concealing his theft by making false declarations on the amount of cash he was holding in his Post Office safe. The suggestion being that he was requesting more than was needed and that that there was never £16,000 in the safe on the morning of the murder because he’d stolen it.

Two Post Office witnesses testified against him, relying on data from the Horizon computer system. One investigator said the amount of cash he’d been requesting for his branch account was suspicious and indicative of fraud.

Garbutt’s lawyers now argue, in essence, that key parts of the Horizon-related evidence cannot be trusted given what’s emerged from the public inquiry into the scandal and fresh evidence from other sources.

Diana’s mother made clear in an interview earlier this year she believes her son-in-law is guilty saying he was “jumping on the Horizon bandwagon”.

But Garbutt’s supporters say, given all the evidence and discrepancies that have been uncovered over the years, he never got a fair trial and it’s time for a wider look at his case.

“We believe that fresh evidence and other important developments that have come to light since the original trial, now mean that Mr Garbutt’s conviction is not safe,” says his solicitor Martin Rackstraw from Russell-Cooke, who along with James Sturman KC have been representing Garbutt for some years.

Conservative MP Hollinrake has written a letter of support. He went to the same school as Garbutt but says that’s not why he’s given his backing for a review.

He told the BBC: “I can’t speculate whether Robin Garbutt is guilty or innocent, but I think we all want to make sure that people when they go through the justice system get a fair hearing.”

Garbutt has failed three times already to persuade the Criminal Cases Review Commission to send his case back to the Court of Appeal as new information has come to light.

At his last attempt in 2021, his legal team raised the lack of knowledge about the Horizon system, but the application was dismissed because the watchdog decided the flaws in Horizon didn’t affect the reliability of the data used by the prosecution at his trial.

“I think this is the final roll of the dice,” says his close friend and former neighbour Barry Conachy.

“We’ve never doubted his innocence and we’re all really hoping this is the one that gives him a breakthrough. Robin’s always said that he wasn’t stealing any money from the Post Office.”