Simon English: Why don't they lock up all the bankers? Well...

Outlook If you are inclined to think that the City sometimes seems like a Mafia gang conspiring against the public, be assured that this scandal is hurtful to even the banking world's most ardent defenders.

David Buik at BCG Partners, an old hand with decades of experience, may have been dipping into hyperbole when he told me that "yesterday was the worst day of my life", but he's not alone in feeling a link between the integrity of the City and his own self-regard. "To be confronted with a problem of this magnitude, to see how Barclays was behaving, is dispiriting to say the least," he said.

I asked one of the City's most senior banking analysts – he asked not to be named – why this wasn't a criminal case. He replied: "The likes of you and I would expect to be heading for jail if we conducted our business in the manner described, so perhaps your question really ought to be directed at the Financial Services Authority."

The FSA says, and the FBI seems to agree, that there wasn't enough evidence of criminal conduct to be sure they would win in court.

There is no doubt the Barclays traders, in league with supposed rivals at other banks, schemed to fix global interest rates.

Barclays traders did, or tried to do, something extremely egregious and they did it to all of us. But it is hard to prove for sure that they had much success. In other words, beyond what they made for themselves personally, they weren't even very successful conspirators. There are few other misdeeds that allow forgiveness on grounds of incompetence.

Another reason for the lack of prosecutions is that for technical, possibly outdated reasons, Libor is "not a qualifying instrument" for the FSA's market abuse regime.

Why? Probably because Libor was once this entirely functional piece of information that the regulators were slow to realise had become just another source of speculation. The watchdogs were behind the market. They probably always will be.