In a tiny Tuscan hilltop town not far from Chiusi, there is a modest trattoria which I will call Lilla, perching on the downslope of one of the steep streets that draw the eye towards Siena. Some years ago, I had reason to spend a while in the town, and being there, passed many lunchtimes eating alone in the restaurant.

The food was typically simple. A thin piece of pork with a contorno of herby lentils perhaps, or pici, thick spaghetti served with tomato, sometimes hare. There would be a quarter-litre of red wine in a carafe, stale, salt-light bread and a bottle of lightly-sparkling water. My meal took about half an hour, and apart from a cheery greeting to the elderly proprietor, my only verbal engagement would be with the lone waitress who read out the day’s dishes at the table and heard my order. I’d eat, pay the bill, hand her a Euro, call goodbye and walk out into the sunshine.

It was always the same, more or less. And more the same than anything else was Giulio. He must have been 75 at least, stooped over lean in his grey jacket, face encumbered by sun-worked skin that sat in comfortable, dark folds. He knew the proprietor well, and she greeted him every day not quite like family.

I don’t think Giulio’s wife was alive, though he wore a ring. We often ended up eating much the same thing, because there were normally only three or four dishes available. I’d mouth a buongiorno if I arrived after he did, and occasionally we’d nod at each other, miming satisfaction at the food and raising a glass across the room. If we left at the same time, which we sometimes did, I’d offer him a light at the door for his shaking cigarette. I ate alone out of necessity and for pleasure. Giulio, I think, did it for the companionship and perhaps insurance against dying unnoticed.

You can tell a lot about a restaurant by its attitude to solo eaters. That moment when the waiter or maître d’ enquires how many of you are dining is a challenge. ‘Just me’ is defensive, while ‘one’ sounds silly. It’s often a relief in these situations not to speak the language – holding up a digit maintains a bluff of confidence.

Restaurants in England are often terrible at this. Requesting a table for one marks you out as someone who has the gumption to occupy a table for two without the concurrent spend on food and drink, and perhaps even worse, as some kind of strange loner, the sort who might go crazy in public or start talking to themselves. And they let you know it. I try to sit at the bar if I have to eat alone in England. Americans are far better: welcoming, generous and non-judgmental.

Of course, there are ways around the problem. Books fill a conversational gap, but remain resolutely anti-social. More pernicious to the institution of solo dining is the smartphone, which has insinuated itself into acceptability to the point that we hardly notice its presence. Smartphones in restaurants are isolating because they create an illusion of social engagement while increasing detachment from the actual human bodies in the restaurant. You can’t have a date with a webpage, though it’s easy to understand why you might want to.

Why do people eat out alone? Normally, for me at least, the answer is work, though for others the reasons are sadder. Stuck in Frankfurt or, heaven forbid, Brussels, it’s food or booze or bed, and food seems best (though Frankfurters often disappoint, culinarily).  If that makes it sound like a chore, it shouldn’t. While you wouldn’t want to everyday, there can be unparalleled pleasure in dining solo. The exquisite pull of privacy and self containment with the pushing consciousness of community and shared experience is a joy. The space to think is rare – like walking or gardening or cooking, eating is an activity that can lighten the mind, allowing gaps to open up, things to be shaken off, and thought, proper thought, to leech in.

And then there is the freedom; or perhaps it’s the decadence? Shall I have a starter? Shall I have dessert? Shall I have wine, or water, or both, or ginger ale, or heck, shall I have a milkshake?  Shall I be a vegetarian? Shall I order offal, nutty gizzards and pissy kidneys? Shall I ask the waiter to recommend something? Shall I eat all the bread? Shall I go to a Japanese restaurant in France? Shall I eat quickly, falling on my food and bolting it down, or shall I take my time, pretending to sophistication and manners that I don’t really possess? Shall I, could I, eat madeleines? You might be anyone on your own in a restaurant.

Last month, I spent a couple of days in Lille covering a conference on genetic therapies. I arrived in a late-evening sleet storm, checked in and trudged out in my only heavy boots. Around a couple of corners, I picked the cosiest, busiest looking place I could see, entered and hung my coat.

There were, reassuringly, four of us lone diners: three men and a woman. In Europe at least, it’s not common to see women eating in restaurants alone. The man closest to me had ordered the menu gourmet, which I thought magnificent of him as I went for the basic formule. My snails arrived, his oysters went; his sweetbreads came, I nibbled on bread. My steak arrived alongside his, and we smiled and he ordered himself another glass of wine. The woman played with her phone as she ate coquilles St Jacques, and the other man drank Flemish beer with a skate wing. I had a crème brulee while working up stories about the couples and families who occupied the rest of the room, and wishing I’d ordered cheese. This was luxury: not work, though because of work; and not leisure, though pleasurable; it was a break in the chain of existence, a moment out of time. Because if you’re alone in a restaurant and no one knows you there, and no one knows that you’re there, then that moment is yours entirely.

You wouldn’t want to do it every day. Not at all. The single diner is an uncherished, lonely beast. No matter how comfortable you are in your head, eventually you can fill it too much. And as the space of solo eating increases, the room for fertile (or perhaps fertilised) thought might start to decrease. Ideas start to nag. Humans are not supposed to be on their own. Is it even allowed, this self-indulgence?  If we are not social creatures, then can we really be said to be in the world? Pleasure in solitude is degenerate.

I’ve not been to Lilla in more than six years, but the last time, I remember, Giulio was there. I’d like to say he was full of life, but that’s not true. He was closer to the opposite, almost lived out. I’m sure there are people who will notice when he stops coming in for lunch – the proprietor, probably. But if I was starting again tomorrow, dropping in for pappardelle al cinghale for the first time, I wonder if there’d be any trace of him.