Margot Kidder, who has died aged 69, will be remembered best for one defining performance. It’s her sterling and witty turn as Lois Lane in the Christopher Reeve-led Superman movies of the late 70s and early 80s, in which she was every inch Clark Kent’s equal in wit and moxie, if not in Kryptonite superpowers – and which set the standard for any other actor playing the role since.