The author seems to think that older pupils raping and molesting the younger students is alright at public school, which it seems he thinks was going on, and potentially to Knight. Similar non-concernedness covered Knight and Fleming's obsession and initiation into Alistair Crowley's coven, as though it's just like having a cup of tea.
When you get past the fact that this slightly odd character could have been a lot more than that, but the author couldn't be bothered to tell you, possibly due to some low moral bar which he's applying, I still would say that this is really quite good. It's like Spycatcher, and as well, the author of which, states that Knight was "brilliant".
I'm left not knowing whether Maxwell Knight was a good agent and boss, but a hapless and confused homosexual (practising or not was not covered) in his private life, or whether he was actually a much more sinister character. I have been left suspecting that he was just a confused person, who didn't really know how to behave in his best interests, therefore, despite his kindness and likeability, he often let those who were around him down. He was a total success career wise, but the relatively mundane stuff he was doing and the inert nature of MI5 prior to and following the war, was not very exciting.
In all, I think there could be a sub-plot (not intentionally put in by the author) that MI5 was a cover for more sinister activity carried out by other organs of the state. They deliberately used flamboyant homosexuals, who couldn't keep secret and boasted about their jobs there, so could never be expected to much good, thus, their underfunded shenanigans made the concept of there being a proper James Bond-type organisation seem unlikely.