The day that Gordon Brown became leader, the headlines made it clear. “Gordon will become the first Prime Minister in 80 years not to use Chequers.”

His aides explained that Mr Brown would be mothballing the 16th-century retreat. Why would a Presbyterian Scot want an English stately home with butlers and cooks, floral valances, four-poster beds and Wedgwood china? John Prescott may have fallen for croquet at Dorneywood but the Roundhead Prime Minister would never succumb to such fripperies as swimming pools and tennis courts.

But despite the Browns' insistence that they would never want a country pile, they have become obsessed by their new home. Where once Sarah could be seen on Friday mornings queueing up at Euston Station for her supersaver ticket to Edinburgh, now she piles the pushchair and the Lego into the car for the hour's drive up the A41 to Buckinghamshire.

It started when Mr Brown was called back from his bucket-and- spade holiday to manage the foot- and-mouth outbreak last summer; His wife refused to spend August in Downing Street so they retired to Chequers and were soon smitten.

The Browns have now used the house for everything from birthday parties to girlie sleepovers (which Mrs Brown has paid for herself). Posh and Becks have been invited, one better than Tony Blair, who only managed Charlotte Church and Geri Halliwell. The guest list, published this week, against Mr Brown's wishes, shows that the house has been filled most weekends with friends, editors, sportsmen and actors, as well as politicians.

John and Fraser play football on the lawn. Sarah now takes guests on elaborate tours of the house, pointing out everything from the ring belonging to Elizabeth I to the Blairs' old bedroom. Squire Brown has even invited local dignitaries, such as Sir Leonard Figg, to tea.

In Downing Street Mr Brown refuses to relax - he eats a bacon sandwich at his desk. Sarah can't put her feet up either. With no cook and only a part-time cleaner, living in Downing Street comes as a shock to most prime ministers' wives. They may be living in the grandest address in London but they still have to clean out the bath and peel the potatoes.

Chequers, however, is different. As Stanley Baldwin said: “There are three classes that need sanctuary more than any others. Birds, wildflowers and prime ministers.” Chequers is a refuge.

The house's motto is, “All care abandon ye who enter here.” Neville Chamberlain unwound by measuring the girths of the trees. Churchill not only addressed the nation from Chequers, he defaced its most famous painting, Rubens' fable of the Lion and the Mouse.

For the spouses it gives them the chance to be pampered. As Norma Major, who wrote a book about the house, said: “What woman would not relish the thought of being relieved of all household responsibility for two days out of every seven.”

Margaret Thatcher was horrified by the cost, turning off the heating for the swimming pool (Gordon Brown has kept it on). If anyone asked how Chequers was run, she would say: “On a shoe string”. She complained endlessly about finding the money to redecorate the walls with her favourite Laura Ashley paper. But she wrote in her memoirs: “I do not think anyone has stayed long at Chequers without falling in love with it.” During the Falklands war she would ask the War Cabinet to convene at Chequers because she felt the atmosphere, “helped to get us all together”.

Cherie loved Chequers so much that she has bought her own mini version, South Pavilion, once home to Sir John Gielgud, and has now poached the housekeeper Ann Hubble from their old grace-and-favour home. Alan, the cook, would make pies for them to take back to London. According to Cherie, “Chequers was the one place in the world where Tony could just be a dad.”

However, it is the dour Scot who has had the most dramatic conversion. It was a brilliant tactical move for Arthur Lee, the Tory Minister of Agriculture, to give the nation his 16th-century house as a weekend retreat for the Prime Minister of the day in 1917. No prime minister, however socialist, has ever failed to succumb to its charms.

Chequers epitomises English country living. Hidden in a fold of the Chiltern Hills, only 40 miles from London, everyone is beguiled by its modesty. Built of russet brick with tall chimneys, it is the perfect size. The gardens, filled with oaks and birches, are welcoming rather than formalT there is even a public footpath running across the front drive.

All the guests mention the loyalty of the staff. When Boris Yeltsin arrived for his visit he was so worried he wouldn't like the food he brought black bread and Russian Coke. When he left the housekeeper had wrapped him up some Stilton and sage from the garden because he had loved the combination so much.

The 1,000-acre estate may cost £1,738 a day to run but Mr Brown no longer seems to care. Chequers is where he feels at home. All he needs to do now is follow the example of Ramsay MacDonald, the first Labour Prime Minister, who took to wearing Lovat tweed plus-fours to get the most out of his new estate.

But Mr Brown's obvious enthusiasm for the place also has its roots in some less comfortable political realities. The son of the manse's previous power base in Scotland is now ruled by an increasingly triumphant Alex Salmond. His home in Kirkcaldy isn't the safe haven it once was.

The Prime Minister knows that the next election will be won south of the Border, closer to Buckinghamshire than the Firth of Forth. Perhaps he is drawing inspiration from Chequers, hoping that its quintessential Englishness will give him an insight into the hearts and minds of Middle England. That's his best chance of holding on to both his job and its tied cottage that he has unexpectedly come to appreciate.

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