In the newly refurbished kitchen at the Cabinet War Rooms two weeks ago, Marguerite Patten, the doyenne of wartime cookery, was clutching a small silver tray. On the tray had been placed a small bowl of sugar, a pat of butter, one egg, some flour and four or five bacon rashers. During the era of rationing, these five ingredients comprised the basic weekly food ration. Other ingredients could be eaten, but many of these were also restricted.

Patten had been drafted in to help celebrate the completion of phase one of the restoration of Churchill's wartime quarters, a £19.5m project that will culminate in the opening of the world's first dedicated Churchill museum in 2005. Accompanying Patten in the kitchen was the celebrity chef Gary Rhodes. To the sound of clicking cameras, the pair stood in the cramped, galley-like space where Churchill's chef, Georgina Landemare, had prepared his meals 60 years earlier.

During the war, Patten worked as an adviser for the Ministry of Food, travelling up and down the country and showing people how to make use of their rations. Subsequently, she has spearheaded the mini-industry catering to the popular nostalgia for wartime cookery, writing more than 160 books, with titles such as Postwar Kitchen and The Victory Cookbook.

The war and its aftermath are usually seen as the low point in Britain's culinary history, a period of unparalleled deprivation from whose shadow we have only just emerged. According to Patten, however, this is an unfairly grim picture. "The diet of many poor families improved during this period, since everyone received exactly the same ration. And because butter and sugar were restricted, rates of tooth decay and heart disease also fell."

In addition, she says, there were various culinary upsides. Under the Ministry of Food's exhortations, people became interested for the first time in extracting maximum nutritional value from food. As a result, many old-fashioned cooking methods, such as the Victorian habit of overboiling vegetables, were abandoned (although anyone who has been to boarding school may disagree with this). Forced to cope with substandard ingredients, people also became more inventive. "The flour was often of such poor quality that it couldn't be used to make ordinary pastry, so people experimented with more crumbly toppings." This, Patten claims, was how fruit crumbles originated.

Patten's recollections certainly seemed to inspire Rhodes. One war-era classic she mentioned - bacon rissoles - prompted him to ad lib a modern version of his own. Putting on his best Masterchef voice, he said: "If I were making them today, I'd dip the bacon in an egg-and-breadcrumb mixture, and then slowly fry the rissoles in butter. Next, I'd introduce an Irish influence, such as mashed potato with spring onions." So, I asked, should future visitors to his restaurants expect to see special "ration-era" dishes on the menu? "You know," he replied, "that's an excellent idea."

Unfortunately, there were no wartime delicacies on offer, despite the kitchen having been fitted with two genuine 1940s ranges. As a result, I still don't know what Spam fritters - the nation's most popular dish in the 1940s - taste like. For the adventurous (and perhaps masochistic) among you, here, adapted from Patten's own Spam: the cookbook, is the recipe:

1. Make a thick batter from 1 cup all-purpose flour, a pinch of salt, 1 large egg and f cup milk, water or beer.

2. Cut 12oz of Spam into eight slices.

3. Heat 2-3 tablespoons of oil in a frying pan until a cube of day-old bread turns golden in 1 minute.

4. Coat the Spam slices once or twice with the batter and then place them in the hot oil, cooking for 2-3 minutes on either side.

5. Drain on paper towels, garnish with fresh herbs and serve with a scallion mash.