Q. I was brought up to stick rigidly to any invitation accepted and never to ‘chuck’ when a better one came along. Recently, therefore, when invited to lunch at Boisdale to meet my favourite actor on the same day as a long-standing invitation to lunch at White’s with an old friend, I didn’t chuck the first invitation for the ‘better’ (because unrepeatable) one. Later, I wondered if it is ever acceptable to play Invitation Trumps — to just be honest and say: ‘I’ve had a once-in-a-lifetime opportunity to meet X on the same day as I’m meeting you. Would you mind if we postponed our lunch?’ What is the protocol, Mary?
— Name and address withheld

A. Invitation Trumps only works if the person being chucked is brimming with self-confidence. Such people are generally thrilled to be chucked at the last minute. They have more than enough demands on their time and would welcome a three-hour window opening up. Chippier people would take it badly, despite the lack of logic — and selfishness — in this. It could be a real blow to their self-esteem. As a general rule, unless the invitation issues from the top of the royal household, you should stick to your original commitment, but by all means let a third party reveal what you have passed over to honour it.

Q. My gardener has imposed two straight lines of ghastly striped petunias, gifted from his own excess stocks, on the approach to our otherwise beautiful 15th-century country house. Creeping about by night with weed killer feels undignified, and that part of the garden has anti-rabbit fencing, so emulating a targeted leporine attack is also out. What should one do?
— M.R., Norfolk

A. Knock up a schoolboy-style sneezing powder mixture using white pepper, black pepper and chili powder. Sprinkle a little on your hand, rub your nose, then stand by the petunias sneezing. Tell your gardener that it’s absolutely extraordinary but you seem to be allergic to his fabulous flowers. Sadly, you must ask him to replant them in his own garden.

Q. I’m going to stay on a Scottish sporting estate for a few days but can’t think what to give my host, who already has everything he could possibly want. I don’t want to arrive empty-handed, though. What do you suggest, Mary?— M.B., Florence

A. Order a copy of Birdsong (published 2012) by Jonathan Elphick, a compilation of text and photographs of 150 British and Irish birds, which comes with its own sound module to play examples of the various songs, cries, shrieks and beak drummings (as in woodpeckers) at the touch of a button. This would make an excellent house present for any sporting lodge, as it can be used for after-dinner games to see who can win the most points for identification. The book costs less than £20.