This week MI5 released Kim Philby’s confession, a yellowing, two-page document half-redacted and tattered from repeated handling. Seeing this piece of history emerge from the past was an eerie experience. I have spent a lot of time inside Philby’s head (not always a comfortable place to be) and here, at long last, was a glimpse into his state of mind just a few days before the most notorious spy in British history fled from Beirut to Moscow and into permanent exile.

Philby wrote his confession in January 1963 after he was confronted with evidence that he had been a communist spy for nearly 30 years. Eleven days later he called his wife to say he would be late for dinner and boarded a Soviet