Philby wasn't trusted from 1951 onwards, he was sacked from SIS and caught in lies by interrogators - using things like his wife's passport stamps to capture hi

Philby wasn't trusted from 1951 onwards, he was sacked from SIS and caught in lies by interrogators - using things like his wife's passport stamps to capture his movements. Technology these days may enable mass surveillance but historically the same thing happened - because there was much less international traffic. MI5 could "burgle their way across London", open all the international mail it wanted to, read the telegrams sent abroad etc. The sheer change in volume of international travel and communication is recent.