You learn to rely on a few basic movements and use your voice to the greatest extent possible to convey your emotions. So there was a technical challenge there and a responsibility to create a character from behind the mask.
“May I share with you my earliest memory of a political row? It was with my mother, about the Queen - classic Freudian stuff, shrinks would say. I was eight, and refusing to watch the Queen's Christmas Day broadcast.”
“As with anything, you need to keep your creative juices flowing and keep the character interesting.”