Brush up your Wodehouse

If Stephen Halliday - or worse Steve Jones, whose book, Darwin's Island: The Galapagos in the Garden of England, he was reviewing (Books, 2 April) - doesn't know that the phrase about the ease of distinguishing a Scotsman with a grievance from a ray of sunshine is P.G. Wodehouse's, he should brush up on his humanities.

Patrick Curry, London.