Indeed he did psingh -- and like you I was amazed that such an intelligent well-read bloke could be so dim. Also a signatory to that letter was William Boyd, a writer I once very much admired until he joined the witch-hunters.
Le Carre wrote some good stuff (Spy who came in from the Cold is brilliant) but about a couple of years I tried to read The Little Drummer Girl and it's truly awful -- so clumsy and turgid that I threw the damn thing across the room.