Well, there was no vocal support of the Khmer Rouge. There was SAS support that everyone kept denying. The SA sanctions thing was a bit more inbteresting and complex than simply being down to the fact that Thatcher was a pro-apartheid racist. I refer you to pps. 320-334 of John Campbell's Margaret Thatcher Volume 2: The Iron Lady.
Yes, the SAS military training of the genocidal Khmer Rouge that ran from 83 to 91, and public utterances along the lines of the one i mentioned and:"the more reasonable ones in the Khmer Rouge will have to play some part in a future government".
Lets not also forget the continued support and arm sales to the genocidal Indonesian dictatorship, support and apologetics for US backed atrocities in central America (“the American government have stated time and again that they are seeking a solution by peaceful means to the problems of Central America”), arms sales to Iraq (and Iran) post Halabja, dirty tricks and army complicity in loyalist murders in NI etc...
As for SA... sure it was complex, but the fact that even David Cameron has disowned Thatcher and Reagan's morally deficient 'constructive engagement' policy tells you all you really need to know... regardless of her concerns about 'stability' (always used to justify monstrous policies), she vociferously opposed the sanctions movement and demonised the ANC.
I guess the really sorry fact is that Labours foreign policy record is even more reprehensible.
I can feel Droid composing an enormous post with lashings of links. (Holds breath.)
Sorry to disappoint Oliver. Its not really necessary TBH