Tom Hayes is angry. Nothing new there — he has been furious for 14 years.

“It’s been a quarter of my life,” he says. “I’m now nearly 47. I was 32 when I was arrested. Ever since, I have been fighting to clear my name.”

Not just Hayes, the former UBS trader who served five-and-a-half years in jail after being wrongly convicted of manipulating the Libor interest rate, used to fix borrowing costs on personal loans and mortgages. Last week, he was joined by five former Barclays traders, Jay Merchant, Jonathan Mathew, Philippe Moryoussef, Alex Pabon and Colin Bermingham, who have had their convictions quashed by the Court of Appeal in London. The same court has also allowed the appeal of ex-Deutsche Bank trader Christian Bittar for conspiracy to defraud.

Another, Peter Johnson, convicted in October 2014, is still battling. Carlo Palombo, a former Barclays trader sentenced to four years in prison in 2019 for rigging Euribor, the eurozone version of Libor, also had his conviction quashed on the same day as Hayes, in July last year.

In all, 37 traders were prosecuted here and in the US for manipulating Libor and Euribor. Each day in London, banks would submit an estimate of the cost of borrowing cash from other banks and an average would be taken to Libor benchmark. A similar process occurred to set Euribor, Ironically, while the campaign for justice carries on, Libor has been scrapped. Euribor still operates.

The desks making the submissions would look at the interest rates at which other banks were lending, how they differed from each other by one hundredth of a percentage point or two, and suggest a rate from within that range. The traders would ask their desks to go high or low — depending on what would benefit their banks’ trades.

It was this, said prosecutors, that was tantamount to conspiracy to defraud. But the traders maintain they were breaking no rules and everything they did was known by their employers, the regulators, which in London, meant the Bank of England.

There are suggestions that even governments played a part, encouraging them to reach a figure that would help instil consumer confidence.

So far, only one of the Barclays acquitted, Merchant, has declared his intention to sue his former firm. Others may follow. Hayes’s case in the US against UBS — he is seeking $400 million in damages — is progressing. Compared with the scale of the Post Office innocents, this is narrower in numbers directly affected but its ramifications are arguably broader. Sir David Davis, the Tory MP who has fought relentlessly on the traders’ behalf, as he has done for the Post Office sub-postmasters, says: “While the Post Office may be the widest miscarriage of justice this country has seen, this one is the deepest.”

Here, seemingly, was a bunch of unscrupulous bankers raking in company profits and their bonuses from exploiting a figure that affected the everyday lives of ordinary people. Its exposure, coming so soon after the 2008 crisis, seemed to confirm everything that was wrong with the City, with the banking industry, the most flagrant example of arrogant City slicker behaviour, playing fast and loose with the household finances of millions.

Hayes was the first to be convicted and to have his conviction overturned. Rather than disappear quietly, however, he has maintained a relentless campaign of redress and has encouraged and inspired the rest. On his acquittal, Pabon singled out Hayes for special praise, saying he “refused to let it go and pushed this through for all of us”.

What they all went through was hell, says Hayes. “Everyone — the media, politicians — said terrible things about us.

“A then regulator made a speech that was so biased it almost caused my trial to collapse and a new jury to have to be sworn in.”

Even now, they remain outcasts in the City.

“I had a criminal record until recently,” says Hayes. “I’m persona non grata in the banking world and it’s the same for the others. None of us have gone back into the City.”

While he was in jail, Hayes was hit by the Financial Conduct Authority seeking to ban him from the City for life. “How could someone in a maximum-security prison [he was serving alongside terrorists and the Hatton Garden heist gang], who was restricted to receiving four visits a month, whose mail was censored, be a threat to the investing public?” he laughs.

Hayes managed to get the watchdog’s move stayed, pending the outcome of his appeal.

But he was not so fortunate in other respects. His conviction cost him his marriage, though he and his ex-wife Sarah, a corporate lawyer, remain on good terms and she campaigned for his release. They have a son together.

“He was 15 months old when I was arrested and he’s just had his 15th birthday. That’s how long this has been playing out for me.”

Leading the charge against Hayes and the other traders in the UK was the Serious Fraud Office. Its director then was David (now Sir David) Green. He is refusing to back down or concede he and his colleagues were wrong. Hayes is suing UBS not the SFO, but Green has chosen to intervene personally in that litigation, on the side of the bank.

He has filed a deposition saying that “evidence that UBS managers knew about or were actively engaged in attempts to manipulate [Libor] submissions was not relevant to my decision to charge Mr Hayes because, in my opinion, Mr Hayes committed criminal offences even if others knew about his activity or were engaged in similar activity”.

Mathew, one of the former Barclays traders whose conviction is now overturned, said that Green, who led the SFO for six years from 2012, should give up the knighthood he received in 2018 for services to the criminal justice system. “The SFO has proved time and time again it is not fit for purpose. It needs to be folded. It wasted £36 million on this Libor investigation and it has been a public disaster. Green needs to give his knighthood back and be held to account.”

Mathew was just beginning what he hoped would be a stellar career at Barclays when he was asked to stand in for his boss and submit some simple readings used to set interest rates for loans between banks.

“It was a 30-second job. Fast-forward 15 years and you’re in prison,” he says. It was like having a “grenade thrown into your life”. He missed two years of his baby daughter’s life and had to sell his family home to help pay for his defence.

In an echo of the Post Office scandal, Davis is calling for an inquiry. “They need to open up their records, find out why these people were pursued, who originated it and who knew about lowballing, and who was covering up.”

He’s found an unlikely ally in John McDonnell, the former Labour shadow chancellor and chairman of the all-party parliamentary group on investment fraud. McDonnell says: “The state not only failed these people, the state was complicit; first in the collusion that enabled these egregious miscarriages of justice to happen, and then in the cover-up that followed.” McDonnell described the traders as “innocent individuals thrown into David-versus-Goliath judicial battles they were always going to lose”. He adds: “I can only hope that the current iteration of our government is as authentic about wanting the state to put wrongs right as they sometimes claim to be. If it is, there’ll be a proper, independent inquiry, and of course full redress for the victims of this judicial and state failure.”

Mathew agrees. “The SFO should be held accountable for what’s been a public disaster and the banks, judiciary and central banks all have questions to answer.”

The SFO refuses to budge, like its ex-director Green, staying firmly to the line it was right to do what it did and there were cases to answer.

On it goes, the City’s Post Office, similarly with no end in sight.