There is this noise, a particular undulating ambient hum, like a human steam train. I’d recognise it anywhere, in any language, in any room in the world. It is the most attractive, whinnying, more-ish sound. It’s the sound of a contented, convivial restaurant, working, well-oiled, tuned, confident. Nobody’s too drunk, nor too sober, there aren’t too many tables of single testosterone-rich bankers or career women out on a single girls’ moan. The waiters are stoking in time to the rhythm of consumption, there are enough couples who fancy each other and want to talk about it and enough matched tables who are truly pleased to see each other. The laughter isn’t strident and the sound level never rises to a shout and never falls so that you can hear the conversation next to you. It is the most complicated recipe, you can’t measure the ingredients or write it down. You can’t teach it and what works in one room will be poison in another, but if you can manage it, properly manage it, conjure it up, it’s money in the bank, and a queue in the reservations book. It is the closest thing you’ll ever hear outside of a playground to the, sound of joy.