I've just watched Tinker, Tailer, Soldier, Spy, the recent film version. That does have the element of lacking trust, one mole, and they knew there was one, can wreck havoc.

I did have the experience in real life. One of my 'friends' was passing intelligence to someone who was misusing it. All my friends became 'friends' because you don't know - very unpleasant.

I think that's why we had so many infiltrators on the 1950s: once one's in, then Philby, Burguss, Blunt... etc, because the first in, leaves the door open for the others.

I have the soundtrack to Casino Royale playing now: it makes typing jolly exciting.