Before his conviction on Monday, Tom Hayes, a 35-year-old former UBS and Citigroup derivatives trader, argued he had merely been taking part in a widespread practice of manipulating the Libor benchmark of interest rates. Sentencing him to 14 years’ imprisonment, Mr Justice Cooke saw things differently. “The fact that others were doing the same as you is no excuse,” he said.

The past five years have seen the exposure of a litany of financial wrongdoing yet a dearth of criminal prosecutions, generating uproar that has now been heard. Hayes’s conviction shows that prosecutors and judges are serious about punishing financial crime — and, they imagine, thereby preventing it.

But their new zeal might not matter much. Everyone might be doing it, but not everyone can be prosecuted or jailed. Even if another dozen traders are sentenced, most of the people who manipulated Libor will go free.