I saw a biopic about Morecambe and Wise recently. The actors impersonating the comedians were not a patch on the originals — how could they be? You need a genius to play a genius. I often wonder if my own HBO Peter Sellers movie would have been improved if someone fiery, of the calibre of Gary Oldman or Sacha Baron Cohen, had been cast instead of Geoffrey Rush, who was muffled under prosthetic make-up.