I found the plot exciting - when I read thee preview in the newspaper :(
I'm wondering if it is a mistake that everywhere is said that he vanished after three years because his children were much older. ???
"Nothing hurts you like the truth." ("What's she like", Roxette)
His defection from Beirut was January 23rd, 1963, as Nicholas Elliott, being an ex-friend (carrot), circled and the genius Skardon (whip) was scheduled to conduct a series of "friendly chats" upon his return to London.
His (first) unmasking was made public in 1956, but he brazened it out and with insufficient evidence against him he was dropped from the service with no furher action taken, and then quietly re-recruited at the end of that year.
The thinking, I suppose, was that nobody would believe that a blown spy could ever be used actively AGAIN.