What is the correct response to a stranger who greets you as though you were an old friend?
Patrick Carson, Lancaster

I should mistrust my memory and eyesight. Perhaps we have forgotten the face or voice of a friend. I should welcome friendliness from a stranger. Smile, with pleasure, even without recognition. I use “dear boy”, “dear girl” and “dear old thing” for these lapsus memoriae. But some find these appellations patronising.

I have been married for 53 years and, in the interests of conservation, I dug out last year's Valentine from my wife, crossed out “husband” and put “wife” and sent it back. My wife did exactly the same thing. Will we be condemned or applauded?
John Carder, Anstruther, Fife

Oh, applauded. Valentine's Day has been turned into a national festival by the greeting card industry. Recycling last year's Valentine won't please the stationers. However, it is uncanonical to send a Valentine to one's long-standing partner. Send flowers anyway, on another day.

How should one use programmes such as Skype to contact friends? Unlike telephones these programmes tell users when their friends are online. I find it very tempting to call them, but realise they may already be talking to someone much more important to them than I am. What should one do?
Christopher Evans, Shipley, Yorkshire

I should call them, provided that you do not contact them immediately and every time they are on online. It's marvellous that we can contact friends with the touch of a key. The downside is that such continual contacts are promiscuous. We must beware of becoming online bores.

I have accepted to be best man at a friend's wedding next year but have just been told that the dress will be “black tie” for all guests apart from those on the top table; who will wear “white tie”. I'm aghast and would like to know whether such attire is acceptable, as I'm finding it hard to keep mum on the issue.
AnonyMister, Top Table

It is indeed an honour to be invited to be best man. I think it is pompous of your friends to lay down such prescriptive dress codes. But there you go - it is their wedding. In for a penny, in for several pounds to hire white tie, soup-and-fish. You agreed. Now you suffer. No good being aghast. Try Oxfam for dead men's clothes.

A couple of years ago my two sisters-in-law fell out. Sister A moved away. Sister B now keeps asking for A's address. I have offered to forward a letter from from Sister B to Sister A. Both are in their eighties, and I feel like piggy-in-the-middle.
J.A. Eastwood, Liverpool

This is a matter of prudence and ethics, not etiket. Without knowing the cast of players, it is impossible to give a “correct” answer to your problem. These are deep waters, Watson, and here are family feuds. But I see no argument in manners and decent family behaviour against giving Sister B Sister A's address. Surely she is not proposing to go round to slip an asp in her porridge?

We are coming to England for the first time on vacation. Any advice, please?
Martin Lancaster, Texas

Do not talk politics. The Brits are shy of the topic. Do not travel on the Underground during rush hour. See the tourist sights, such as the Tower of London and the British Library. But get off the beaten track also. Not just Oxford or Cambridge, but Bury St Edmunds or Winchester. The sensible Brits are basically lovers of America. You are our brothers and sisters under the skin and across the pond. Welcome. Have fun.