This is nicked from an edition of The Spectator:
A certain Lord X, in his RSVP to a posh dinner writes:
Lord X thanks Bentley Entertainments greatly for the kind invitation and accepts with pleasure. Regarding his dietary requirements, Lord X does not eat, mushrooms, gravy, aubergine, capers, artificial sugar (or natural sugar for that matter) & wine that is not from the Burgundy region. He is technically glutten-free, wheat intolerant, diary-free and also cannot eat fruit, however he will forgo this for apples. He does like peas and steak.
The reply to Lord X goes as follows:
Dear Lord X, we are delighted you can attend the dinner but, having noted your complex dietary requirements, suggest you eat before you come.