air pig
David Leigh's book "The Wilson Plot" relates how a Treasury Minister, Niall MacDermot was refused a security clearance because of unproved accusations over his wife's Russian origins / connections
https://en.wikipedia.org/wiki/Niall_MacDermot
The same book (same chapter : 7) also relates how a Labour MP , prospective minister, and former CP member, Bernard Floud, was interrogated by Peter Wright (of Spycatcher infamy) and harrassed into committing suicide
https://en.wikipedia.org/wiki/Bernard_Floud
You may be thinking of one or both of these
(Thanks for the reminder PN - I''d forgotten that book until your post)