I was lost in Senegal and saw a police officer. My experience of Senegalese people up until then had been only positive, so I hoped he could help me. I greeted him, asked my question, and he replied in a French-for-idiots that was dripping with contempt, “Here, we say bonjour.”

In this country, it is normal now to enter a shop and not greet the staff, and to leave without saying goodbye

I had said it, he hadn’t heard it because of the traffic noise, but he chose to be an idiot about it. Even though he was being rude about being polite, actually I didn’t mind his censure: one of the things that other countries do far better than monolingual monocultural Britons is greetings and leave-takings. It is impossible to enter anywhere in mainland Europe and not say “buongiorno” or “bonjour,” and it is excessively rude to leave without saying goodbye.

Of course, that’s a minefield too in France: when does bonjour become bonsoir? Nobody knows (and I’ve asked plenty of French people). But try leaving without saying anything. You’ll get the Senegalese police treatment. It is rude.

When I moved back to the UK from Europe twenty years ago, this was one of two things I found difficult, along with being less able to filter out other people’s chat on a bus. In this country, it is normal now to enter a shop and not greet the staff, and then to leave without saying goodbye.