Correction - as of yesterday it should (officially) be "to have a clue who he WAS". Just another of the aristocracy who got caught shagging the nanny and ran rather than face the music!
From what I was told, years ago when I worked in a somewhat rarefied environment where people knew about these things (or thought they did), it wasn't him who was shagging the nanny.
In any case, the poor girl died. There's no excuse for killing someone in cold blood, no matter how provocative the situation. If he had stayed in the country and faced the music, it might have been considered a crime of passion.
Maeght, I take your point about Christopher Eccleston's accent, I thought as much when I watched the programme but after a while I didn't notice it because it seemed, to me, that he captured the essence of John Aspinall perfectly. I don't know much about Lucan so can't judge Kinnear on his accuracy, it seemed alright to me at the time. Families are bound to object to portrayals of their loved ones in drama. I am more sympathetic towards the nanny's family.