Marguerite's the Queen of Spam

Delia Smith has held our hands in the kitchen for the past two decades, Fanny Cradock amused us by overdressing for dinner through the Sixties and Seventies, and Elizabeth David brightened up the Fifties by introducing us to Mediterranean flavours, but it was Marguerite Patten who helped the nation feed itself through the war years of the Forties.

While Vera Lynn sang, she cooked. As a home economist with the Ministry of Food, she showed housewives how to get by with a can of Spam and a ration book. She was a reassuringly familiar, no-nonsense voice on the BBC's early-morning Kitchen Front broadcasts and Woman's Hour, exhorting the country to eat its way to health and victory. In 1947, she became the first female TV cook, mothering everyone through the potato shortage and then startling them with Baked Alaska and quiche as times grew cheerier. "I think I originated the phrase 'And here's one I did earlier'," she says.

At 84, her energy is undimmed. She is not snobby or faddish. She will sing the praises of Spam, even though she is not a particular fan. In fact, she's just published a book on it (Spam: The Cookbook, published by Hamlyn, £6.99). "Quite a challenge," she says diplomatically. "It's only a small book."

Over the past half-century, she has written 165 books, clocking up sales of more than 17 million with titles such as Cookery In Colour. "I'm a healthy creature and, quite honestly, I think that's to do with liking good food," she says. "I'm one of the lucky people who like the things that are good for you, which means the foods of all the world, really."

Last year, Patten published her Century of British Cooking, a decade-by-decade look at how and what we ate during the 1900s, from Windsor soup and devilled kidneys, to polenta and Thai green curries, via Lancashire hotpot, coq au vin and Black Forest gateau.

It is this nostalgic territory that she will be covering when she opens the new monthly lecture series at Leith's School of Food and Wine on 5 September, but to dismiss Patten as an old-guard food historian would be a mistake. She may no longer wield the influence to strip bare supermarket shelves ? la Delia, but, in an age when TV cooks are hired as much for their haircuts and cheeky banter as for their way with a frying pan, she still has wisdom to pass on.

Advising Channel 4 recently on its series The 1940s House got her thinking about how our eating habits have changed for the worse. "I'm worried about the grown-ups, but I'm even more worried about the children who are growing up often without the right balance of food," she sighs. "We kept fit during the War. We had to give a lot of time and thought to cooking because we had such a poor and monotonous range of ingredients, but the children born then grew up strong and healthy. I'm not at all sure whether they will be as strong and healthy today, and that is really quite iniquitous when you think of the range of food available.

"I've been asked to wag fingers for 10 or 12 years now about convenience foods. I don't do that because I think if people are very busy, convenience foods have a place, but you should assess where they are deficient. Obviously you need fresh vegetables. I've always said I'd far rather people buy convenience food than have a nervous breakdown because they're trying to do too much. "What worries me with the people who aren't cooking is how do they know if a thing's not good? How will they assess it and say, 'I could do better.' We're going backwards."

This is as close as she comes to sermonising. Certainly, she is far too elegant to hector. She belongs to a generation that answers the telephone with her full number and pronounces lamb as "lem". Her mind is pin-sharp and so is her dress sense - she answers the door at the tidy bungalow where she has lived for nearly 40 years wearing a red suit and pearls. In the sitting room, there is a huge old radiogram and plates with pictures of fighter planes on the wall (her late husband, Bob, served in the RAF). The only sounds are from a quietly ticking mantlepiece clock and the intermittent calls from researchers wanting to know what the weather was like in 1942 or how people bought their meat ("The majority of people would rather the bones were taken out. Not at all. Goodbye.")

The whole place might have been preserved in aspic like one of her Sixties dishes, especially the spotless kitchen, with its Formica surfaces, old Kenwood Chef and giant yellowing microwave. But clearly she has been busy in it on the morning of my arrival: on the dining table is a tray of salmon sandwiches, delicious tiny scones with cream and jam, and buttery home-made biscuits. She still works a full-time week, writing, talking, filming. "My daughter always says to me, 'Mummy, we'll never get rid of you, because if you were on your deathbed and they wheeled a television camera in you'd be up and away'." And, of course, there is the cooking. "It's almost, I think, that we're a divided nation," she says. "Not North and South, or rich and poor, but the ones who love cooking and the ones who don't."