I'm just looking at the DID section of the BBC website.
http://www.bbc.co.uk/radio4/features/desert-island-discs
Fascinating stuff especially when you start searching.
Black Sabbath have never been taken, Quo only once, The Beatles 213 times and Mozart beats Beethoven by about 50 or so appearances.
12 times for Hoffnung's Oxford Union speech
And I wonder if Hugh Grant stands by some of his selections ?