Interesting times Corgi Audio Books 1996 ISBN 0-552-14425-8

The oldest and most inscrutable empire on the Discworld is in turmoil, brought about by the revolutionary treatise What I did on my Holidays.
And all that stands in the way of terrible doom for everyone is…Rincewind the wizard (who can’t even spell the word ‘wizard’), Cohen the barbarian hero (five feet tall in his surgical sandals) – and a very special butterfly…