I generally like Macintyre in the Times, but as PE point out, he really should have removed all the errors about Michael Foot from the paperback edition. The fact that he hasn't makes me question how much other bull**** he's told me over the years. I've been reading since him since he was Paris correspondent.
What errors? Foot was listed by the KGB as an agent.
Gordievsky was so effective precisely because his intelligence was so accurate. Why would you think it would be inaccurate in this instance?
Just because he won a libel case doesn't mean he wasn't. Liberace won a libel case over suggestions he was a bummer. Maxwell won umpteen libel cases over suggestions he was a crook. Now of course it could be the case that the KGB's London station were simply making it up to look good, but there's no archive evidence either way.