Every day, I go out for lunch in a caff, visiting a variety in rotation. I am slightly more food-conscious than most of my fellow diners. At one of my regular places, I tell them to hold the chips in their frequently advertised special "chicken curry, rice and chips" because surely that's too many carbohydrates. As a preliminary, I always have a mug of tea, which comes with the bag still in. I stir this around for a while before flipping it into the stainless-steel ashtray and digging in.

Over the years, I've become interested in the names of the caffs, because these have been chosen in an environment free of stylists, corporate image people or, in fact, any sort of self-consciousness at all. On East Finchley High Road, I sometimes eat at a place called simply Local Cafe. You can't argue with that. I mean, there's no cafe more local to that particular spot than the Local Cafe, which is probably why it was so called. Nearby is the Big Chef, where a takeaway cup of tea will set you back 40p. I once asked the man who runs the Big Chef why it was named that, and he said, "Well, you've got the Little Chef, so . . ." "But is that all there is to it?" I asked, perhaps rudely. "Isn't one of the cooks here particularly tall?" But even as I asked the question, I could see across the counter into a kitchen that contained an above-average number of average-sized men.

Still in Finchley, but over on Ballards Lane, there used to be a caff called Kafka's Spoon, a name almost as perplexing as the Seashore Cafe, which is in the heart of Kennington (if Kennington has a heart). I ate at Kafka's Spoon once but never got around to asking the proprietor why he'd picked that name. Insanity, I suppose, might have accounted for it. Or is there some connection I ought to have heard of between Kafka, spoons and Finchley? Anyway, Kafka's Spoon is now a belly-dancing bar called, I think, Fernando's, leaving only very boringly named cafes along the same stretch: Tasties Cafe and the Quality Cafe.

Another of my favourite names has also recently changed: the Titanic Cafe in N6. It's a brave and interesting entrepreneur who names his business after the world's most famous maritime disaster, but the place is now called the Highgate Cafe, although under the same management. I asked the top man in there what had determined the original name. "Film!" he said, as if it was self-evident. He meant the film Titanic, starring Leonardo DiCaprio, and I suppose he had reasoned that the success of the movie outweighed the failure of the actual boat.

Quite near the Highgate Cafe is another friendly and economical eatery, the International Cafe. You can tell it's international from the cuisine advertised every day in the window: "Egg, 2 bacon, sausage, mushrooms, beans, 2 toast, tea/coffee. £3.25."

Sitting in these places, or cycling or driving past them, I will experience sudden moments of illumination concerning their names. Take the Crescent Cafe in Crouch End. I used to spend ages wondering about that. The proprietors might have been Muslims, and so it could have been an allusion to the crescent moon. But then I looked across the street while eating a cheeseburger, and saw that the cafe was directly opposite Crescent Road. I have also eaten in the Tea Set on the North Circular Road, which I always assumed was named after . . . well, a collection of crockery. But driving by one day, it struck me that it was a pun. The suggestion is that the people who go there are a sort of informal club: the Tea Set.

Obviously, the names are not the only mysteries surrounding London caffs. For instance, why do all builders have at least seven sugars in their teas? Why do all plasterers smoke roll-ups? And how come the caffs haven't all been taken over by Pret a Manger?