[1] As a writer, he has won a BAFTA and an Olivier Award for his work on TV movie Best Possible Taste: The Kenny Everett Story and play Morecambe.

Whitnall began his career in West End musical Elvis in 1977 after winning the role in an open call audition.

[2] He has starred in many West End musicals including Grease, The Rocky Horror Show, and Good Rockin' Tonight.

For this work, Whitnall was nominated for Best First Feature Length Screenplay category in the 2010 Writer's Guild of Great Britain Awards.

It was directed by James Strong, produced by Paul Frift and starred Oliver Lansley and Katherine Kelly.