Is it me, or am I justified in feeling uneasy about the conviction and sentence handed down to former UBS and Citi trader Tom Hayes for rigging Libor?

Last week, six brokers were acquitted of conspiracy to fix the interbank rate. Their walking free was described as a severe blow to the Serious Fraud Office that brought the prosecutions.

But in his cell at Her Majesty’s Prison Lowdham Grange, Hayes could be forgiven for raging against the iniquity of a system that has seen his life ruined.

He was initially sentenced to 14 years, with his term cut to 11 years on appeal. While that is longer than often handed down for killing someone, it was seen as a discouragement to others, a reflection of society’s fury at the cynical disregard of some in the City for the lives of ordinary people.

Hayes, portrayed as being at the centre of a web to set a benchmark used for millions of personal loans, was the worst of the worst, an arch-villain who deserved every moment inside.

"It did not ring true that Hayes was able to act without anyone at the bank knowing and agreeing." Chris Blackhurst

I admit to having had qualms about his case. Hayes, in the banking hierarchy, was a junior. We were supposed to believe that his superiors never condoned what he did. It did not ring true that he was able to act without anyone at the bank knowing and agreeing. That unease increased with details emerging about Hayes and his personality.

He seemed to be a bit of a geek, as many are in his area of work, but he also appeared quite open and personable, not terribly sophisticated at keeping something secret. Indeed, that was his defence, that what he did was common, he was encouraged to do what he did and he did not believe he was acting dishonestly.

So yes, I would have felt much more reassured if his bosses had joined him in the dock.

But the promise of the subsequent trial of his alleged co-conspirators did provide some solace. Then they were acquitted. Hayes said he was delighted with the outcome. He was “thrilled that the brokers can return to their families and their lives” but is “bewildered that he is now in a situation where he has been convicted of conspiring with nobody”.

He’s not alone in his view. Originally, there were 22 names on the draft indictment, including the six just found innocent.

At Hayes’ trial, most of the evidence presented against him was in relation to the six — hence, presumably, the SFO’s decision to pursue only them. Most of the other names were only ever thought to be peripheral.

Hayes says he had never met or even spoken to them; there were some he’d been in touch with via email or other messaging, but just a few times.

Apart from the six, the SFO is thought to have interviewed just one of the other names. None of the 16 have been charged. The regulator may claim that quizzing the rest was difficult due to the fact several of them were overseas and the investigator must be mindful of budgetary constraints.

Hayes’ line manager at Citi is currently in New York, hardly difficult to get to, but he is understood not to have been seen. This is despite the bank being recognised as co-operating by the prosecution.

One of those on the draft indictment is still employed by Citi, but he’s not believed to have been interviewed either. That goes for three more on the draft indictment who reside in the UK — they’re thought not to have been questioned by the SFO.

Ahead of Hayes’ trial, the judge, Mr Justice Cooke, decided to separate his hearing from that of the brokers and his alleged co-conspirators.

Their statements were not allowed to be submitted in the trial of Hayes. Presumably if they had been, given the jury’s conclusion in their trial, this may have assisted his defence.

Critically, his jury was unaware of evidence relating to whether or not an agreement between the co-defendants was ever reached.

After their acquittals, David Green, head of the SFO, said: “The key issue in this trial was whether these defendants were party to a dishonest agreement with Tom Hayes. By their verdicts, the jury have said that they could not be sure that this was the case.”

It’s a curious form of words from Green. He’s trying to justify the prosecution by saying that in the end the jury could not be certain, so therefore they acquitted. Where, though, does the jury say that? Equally, the jury could surely have been certain there was no agreement — Green simply does not know.

In Hayes’ earlier trial, however, without the evidence from his alleged co-conspirators, the jury was certain there was a conspiracy. That does not seem right, or fair somehow.

During his closing speech to the jury at Hayes’ trial, Mukul Chawla QC for the prosecution was keen to point out that Hayes was the first but would not be the last. Presumably this was a reference to the six. But look what has happened.

I am not saying that Hayes is innocent of manipulating Libor. But I don’t see how anyone can be guilty of conspiring with others when no such conspiracy apparently exists.

In the light of the acquittals and the non-submission of the statements from the six in his trial, Hayes deserves another appeal.