Dear Mary: What is the etiquette of greeting a friend who is engaged in a ceremonial display?

Q. Passing Buckingham Palace in a taxi the other day, I saw the ceremonial wing of the Household Division prancing impressively along on horseback. The taxi halted to allow them to pass. As I knew one of the young men socially, I wondered what is the etiquette of greeting a friend who is engaged in a ceremonial display? I can see it would have been disruptive to the integrity of the group if one member had to nod or wave back to somebody, but surely it would have been rude of me not to acknowledge him — even if only to do a ‘thumbs up’? As it happened, I did not catch my friend’s eye, but Mary, what should I do if such a situation arises again?

— M.W., Pewsey, Wilts

A. By all means wave out of friendliness — tourists often do so — but don’t expect a response. Those mounted would not break with protocol in that environment.

Q. I wanted some shirts for the summer that can only be bought in America. Because the company does not ship to the UK, I ordered a few and had them sent to a cousin in America who agreed to send them on to me. This was in March. A few weeks ago I WhatsApped her and asked if she had sent the shirts on. She apologised and said she had forgotten, ‘but I’ll send them now’. They still have not arrived and I feel I cannot ask her again because, in the meantime, she has had a baby and I failed to congratulate her. It seems wrong to WhatsApp her now, three weeks after the baby was born, saying: ‘Congratulations onyour baby and by the way have you sent the shirts yet?’ Mary, what should I do?

— A.H.,