No, thank you Wildrosie! You sent me down a marvellous rabbit hole last night on google and wiki 
Peter Macaleese (the one I probably didn't meet but maybe it was) was also in Angola with that mercenary debacle. I'd read a fair bit about this many years ago and always found it to be rather an interesting (and downright bizarre) tale. Anyway, I clicked through and started reading about Callan and then followed a link and a google search or three as you do and came across a list of the men who went out there. And spotted another name from my own past...Leslie Aspin. I haven't thought about him in decades. Turns out that he was one of the recruiters - I knew the name John Banks very well, the one who is usually named and takes most of the blame (overreaching arsehole that he was) but had no idea of Aspins link. Story follows, slightly off tangent...
Back in 1989 my grandfather was in the Norfolk and Norwich Hospital with pancreatic cancer. Visiting with my parents (I was 16 at the time) we got to meet and know his roommate in a 2-person ward. Nice fella, good company and someone my grandfather (who I remember as quite gruff and not suffering fools though this might have been different from an adults pint of view to be fair) took to and they seemed to get on like a house on fire. We even have a photo of them together somewhere I think. Les, as I recall, was very thin and not in the best of health (obviously why he was in there) and we used to take him a 4 pack of Guinness as the nurses/doctors supported it as being a better and cheaper option than the iron tablets he was supposed to take. Anyway, I recall my dad telling me that Les had been a mercenary at some point (maybe a pilot or something too?) and I remember that he died but other than that very little. Reading this was an eye-opener and I sent it across to my dad last night. Just wow:
www.independent.co.uk/life-style/was-this-man-britains-irangate-fixer-1445398.html
My grandfather started to keep some random company towards the end now I come to think of it. He had a 'friendship' with the mother of Richard (of Richard and Judy) too. My parents and I went around for a meal once and she gave us tinned Heinz tomato soup with cream in it. Massive treat for me as that's my favourite soup but she seemed offended when I put pepper on it and she said that in a proper restaurant that would be considered rude etc. She was well to do and rather pretentious and my dad took exception to us being served tinned soup and her thinking she was some kind of bloody gourmet My dad is usually very forgiving of people...I liked her, he thought she was a snob and an arse and didn't keep in touch.
One last bit...rabbit warren more than hole, my mum grew up in the Belgian Congo (what used to be called now Zaire but is now called now Democratic Republic of Congo ) Northern Rhodesia (which is now called now Zambia) and went to school in the Republic of South Africa (which is now just called South Africa). Anyway, she was there during the 1960's and walked out twice as a refugee when things were getting bad. She remembers the mercenaries, is very scathing of the UN, loved playing football with 'the sikhs' (Indian UN troops stationed nearby) saw a mob waving pangas around and trying to pull gurkhas out of a truck and various other tales of a ditch full of corpses, mattresses against the walls, narrowly avoiding being raped with her mother and sisters in her home as one of the stoned rebels knew her father...I need to record this properly I think.
I'm often amazed at the more outlandish things in my life. Makes me sound like a bit of a walt myself but I definitely wasn't anywhere near the balcony - I was only seven
Anyway, back to the siege, I'm sure the Attorney General story is feasible and would like to know for sure. The geneva convention applies to theatres of war and may well have not applied in this instance...perhaps that's also why the gloves never came fully off in Northern Ireland? Iraq and Afghanistan and terrorists (un-uniformed 'combatants' rather than guerillas which are recognisable as a combatant and theoretically afforded protection by the Convention) are moot points too as from memory neither country were signatories...
Too many rabbits...