1. Misappropriation of public funds
They deliberately falsified data then used the results of the falsification to obtain additional research funding. This is criminal fraud under English Law.
2. Deliberate attempt to prevent disclosure of information that was requested under the FOI Act
They colluded to destroy information that was the subject of an FOI request. This is a criminal offence under English Law.
These two offences will do for starters, but there are others, too. Indeed, both of the above offences can be doubled by charging the alleged miscreants with conspiracy in each case. Jones, Briffa and Mann should be prosecuted as a warning to others who would pervert science as a method to promote a political agenda. However, there is little probability that the Crown Prosecution Service will charge the alleged miscreants. It is more likely that they will be awarded Knighthoods.
And those like Monbiot who colluded in all of this will say, “We did not know”.
more at Joanne Nova's excellent blog