Though I hate to say it, I have to give Cornwell his due in that he openly declared he would never accept a K or a peerage because he found the whole honours system "fatuous".
You say you've only read The Spy Who ..... etc, Keith. It's his best book (and as you say made a very good film) one of the reasons being because it's short. The trouble with his later books is that due to his enhanced status as a best-selling author, editors were reluctant to suggest cuts and tightening up generally. So le Carre became self-indulgent and fell in love with his own wordsmith facility (which was considerable), and with no one with the guts to curb him his books became flabby and meandering. A good editor with the bottle to rein him in and curtail his excesses would have worked wonders for his later novels.