It's 75 years since the Aga was introduced into this country from Sweden and, to mark the event, Persephone Books has republished Good Food on the Aga by Ambrose Heath, which first appeared in 1933.

This fascinating book begins by stressing "the ridiculously small amount of attention" the Aga needs. But the sentence that follows seems to undercut this: "Once the Aga has been lighted, only three operations a day are necessary". As opposed to none, that is, for any other cooker. The instructions that follow, about how to "riddle" the Aga, remind me of the many technical manuals I have read about how to drive a steam locomotive.

The Agas in use today are not usually coal-fired, of course, but the philosophy remains the same. Here is a type of oven that, by its mass, its expense and the fact that it is always on, becomes the centrepiece of the house. The Aga is an anchor of domesticity. It says: we are in this house to stay; we have ascended to our social plateau. The Aga specialises in cooking things slowly, but more to the point for a long time, and, ideally, it should be constantly brewing up some strain or other of English comfort food.

Good Food on the Aga is full of diet-busting recipes for incredibly rich sauces; and when these are completed, there is often a footnote beginning "To further enrich the sauce". One would have to do a lot of walking across one's estate to work off this kind of food, and the Aga also symbolises a country life. Put bluntly, people who own an Aga either live in the countryside or are pretending that they do. A couple of years ago, a marketing campaign began to persuade city dwellers to buy Agas but, as the countryman Adam Edwards pointed out at the time: "While the Aga may be a jolly useful way for drying out a pair of stout walking boots . . . it doesn't do much for a pair of Manolo Blahnik heels that have been splashed by a Sea Breeze at the Ivy."

The London Agas are generally in south London: Wandsworth, Clapham, even Tooting, and they're owned by middle-class folk whose aim is to earn enough to move out to the country in style or (secretly, subversively) to earn so little that they have to in any case. Their parents lived in Chelsea, with a place in the country, and they're permanently vexed by the compromise they've had to make. It is these parts of London that suffered the biggest losses of people to the countryside during the last recession.

For those yet to make the leap, the Aga in the Clapham kitchen is a symbol of the life to come . . . Except that most people I know who've moved to the country and bought an Aga have come dreadfully a cropper, so that I always think of the Aga as more of an Arrrgha! But that's another story.