I love the idea of Leslie being involved in the cover-up and that being how Meres comes to the attention of the Section! Yes, Snell's file on Meres is no doubt quite uncomplimentary in many ways - but then, Meres' various personality defects can be harnessed for the good of the Section, mostly.

From the novels: Callan thinks that Meres is addicted to killing, and like all junkies, he'll eventually go off the rails; and Meres thinks of the times he's repeatedly told Snell that he can't stand being hurt or insulted by women - after he's lost his temper and killed a woman he was meant to bring back alive for interrogation.

Yes, Meres does always obey orders, doesn't he? Of course, he actually wants to stay in the Section, whereas Callan is dragged back only reluctantly. The Section provides a sanctioned outlet for Meres' sadistic interests and abilities.