Like the Americans, the British are very first-name orientated.
The French do not use first names as readily as we do, and I think this is because the French have not had the same high level of American influence in their culture. In France first names are not used with the same gusto, though this is changing as more and more British and American influence seeps in to the French way of life, much of it via television.
As an older person I do not hesitate to use the first name of a younger French person, if I know it. If I don't know it, but need to because I will be speaking to him/her again, I ask. Oddly, however, they will invariably answer "Monsieur Tartonpion" (or whatever). Now, as I am an older person, I feel free to say, "et votre prénom ?" Note that I am still using the formal "vous".
A young person will accept this quite happily. If that young person then starts to call me Catherine (though I cannot think of this ever happening actually) that would be offensive, simply because I am older. It would show considerable ignorance.
With older people it depends so much on the situation. I am a member of an Anglo-French group and when new French members join it is important that they feel at ease. To help them loosen up I immediately shake their hands and announce "ici, c'est les prénoms. Je m'appelle Catherine." They then give me their first name… which I subsequently forget … because I am an older person!
Although some of them may feel a tad overwhelmed by the familiarity, the group is predominantly British and, on the assumption they have joined to meet British residents of France and/or improve their English, it is perfectly acceptable to launch into the British way of doing things. Which includes first names. It is not a faux-pas, they do not find it offensive – au contraire, it is friendly and appreciated. But there are only certain circumstances, like being members of the same club (in this case the Anglo-French group) where I could do this. In other situations I wouldn't.
If I meet a French person at, say, a dinner party, I will use first names too. It would be ridiculous not to, but I keep the "vous". It is not long ago that it would have been considered rather "forward" to use a first name in this way. On the odd occasion that I feel the person in question is slightly taken aback by my "forwardness" I smile and say "les anglais sont très prénoms!" Any person who is out-and-out offended by it is a person I don't want to know and, as they say in French, they can go cuire un oeuf.
But – you should never use the first name of a person in a formal situation, least of all if they are older (let's say over 40 or so), like the bank manager, a notaire or a doctor. Ever. Not even when you get to know them well at a professional level, unless they invite you to do so. Which they won't. I died a million deaths on one occasion when I was helping to interpret in a notaire's (solicitor's) office and the English woman buyer cheerfully called the notaire by her first name. It was excruciatingly rude. Would she have done that in the UK, I wonder? I wouldn't. A notaire, male or female, is always addressed as Maitre.
Hilariously, some people will insist on giving you "Madame Tartanpion", almost as though it is a status symbol. As if my using their first name would be contemptuous or something. We took on a man to help in the garden for a while and he told me his name was "Monsieur Guillou". I was new to France and just assumed that Guillou was his first name, and that he was trying to keep a touch of formality by putting Monsieur with it. I called the poor man Guillou for the several months he stayed. He'd have done far better to tell me he was Benoit Guillou. He must have found me really quite snooty.
– If in doubt use Monsieur, Madame so-and-so.
– If you feel it is OK to use first names, keep the formal "vous" until they use "tu" with you. Again, that is unless you are considerably younger, in which case stick to "vous" unless invited to do otherwise.
– People in positions of authority should always be addressed formally and you can only consider first names if you meet them socially, with a few exceptions, for example, our garde champêtre (a kind of local police officer) I call Ludovic, his first name, because it somehow works.
– Trust your gut feeling and if you find you have got it wrong, just laugh it off by saying you are English. To that the French love to respond "ah, c'est très compliqué, le français" and then you can agree enthusiastically, smile a lot … and move on.
Catherine Broughton is an author who, with husband Bruce, has lived in France for over twenty years. Her first book, "A Call from France" was published in 2010. For more about Catherine Broughton go to turquoisemoon.co.uk