Oof, I think I might have messed up on the actors' ID's above, so let me try again:
Patrick Stewart : Lord Leo de Grance
Helen Mirren : Morgana le Fey
Liam Neeson : Sir Gawain
Movie moment: the freshly-minted King Arthur (Nigel Terry) dramatically saves de Grance's castle, life and kin via one of the most unbelievable movie moments ever:
https://www.youtube.com/watch?v=XAIeh0YarFs