I saw Jane Horrocks, who the part was written for, and she was very good, but you could still hear flat Rawtenstall vowels creeping through the impressions, which you don't hear as much with Diana.
It is important to the story, because L.V. is supposed to do a pitch perfect impersonation of those female singers.
Mind you I know quite a few men who can do a flawless Shirley, Marilyn, and Judy etc.
