Desig House: Real Homes: A neoclassical pavilion

In Home Counties terms, few houses can be more remote than Bradwell Lodge, tucked away where the Essex flatlands east of Chelmsford meet the sea. Yet few houses of its modest size anywhere can claim a more fascinating history, especially over the past 80 years or so.

Though the landscape is uneventful, this is in fact a profoundly historic area. Two miles to the north-east lies the site of the Roman fort of Othona, built in the third century to protect against seaborne raiders, and on top of it sits the simple chapel constructed by St Cedd in the seventh century, constructed out of Roman bricks and stone. Bradwell Lodge is much more recent in origin - only fifteenth century, with an exquisite late-eighteenth-century addition - but the history that goes with it is more extraordinary still.

Architecturally speaking, the house is made up of a long, low Tudor wing, a regular rabbit warren of low-ceilinged rooms, to which in the 1780s a neoclassical pavilion was added, with rooms that are light and beautifully proportioned. The pavilion was commissioned by Henry Bate Dudley, a local landowner and member of parliament, who drained the surrounding marshes and introduced the latest advances of the agricultural revolution to this corner of Essex. Beyond that, however, his career also had a more picaresque side, with a spell in Newgate Prison for libelling the Duke of Richmond with his journalism - he founded the Morning Post - and covert involvement with smuggling. We can't be sure that his pavilion was specifically designed with smuggling in mind, but it is topped with a glass-sided belvedere room that commands a wide panorama over the flat countryside, from which at night it would have been easy to see the torches of any approaching revenue men.

For his architect, Dudley turned to John Johnson (1732-1814), not a name particularly well known then and still less now, who nevertheless demonstrated just what elegant and sophisticated designs a 'provincial' man could produce in the Georgian period. He divided his career between London, where he designed handsome terrace houses in Mayfair and Marylebone, and Essex where he was county surveyor. His interiors generally show the influence of big-name contemporaries such as Robert Adam and James Wyatt, and this is certainly so at Bradwell Lodge. Here, the front door leads into a low-domed vestibule, which in turn gives into a taller one, domed and top-lit. To the left lies the Tudor wing, while to the right a few steps with scrolling ironwork achieve the change of level into the Georgian wing.

At the centre of the south front, within a curved bow, sits a small but lovely oval library, the bookcases curved to follow the walls and incorporating a remarkable, cast-iron neoclassical stove that remains flush with the shelving until pulled forward for use. To one side of the library lies the beautiful drawing room, which has the most elaborate ceiling in the house, inset with painted panels in monochrome grisaille. Prettier still is the marble chimneypiece, which has top-quality painted panels plausibly attributed to Angelica Kauffmann, whose election to the Royal Academy was promoted by Dudley. On the other side of the library is the dining room, where the chimneypiece frames a grate that can be either expanded or contracted according to how much heat is required. Practical ingenuity is indeed one of the hallmarks of Johnson's house. He carried the four chimneys up to the roof, where they act as the four pillars supporting the belvedere. Access to the belvedere, which is now via a very tight staircase emerging under a low lintel, seems originally to have incorporated some kind of canvas concertina that expanded upwards.

From Dudley's time we fast-forward to 1938, when the house was bought by Tom Driberg. Books have been written about Driberg's incredible and contradictory career: a communist for 20 years, despite being the son of a retired colonial official educated at public school and Oxford; a devout Anglo-Catholic who was variously said to be a KGB agent and MI5 informant; a married chairman of the Labour Party whose gay activities and infidelity, though notorious, were completely ignored by both the law and the press. He never quite had the income to cope with the demands of maintaining a country house, but after the war he was able to tackle a serious outbreak of dry rot at Bradwell with the help of a substantial cheque sent to him from Moscow by Guy Burgess, a former boyfriend. Having no children and loving the house, he offered to give it to the handsome 18-year-old son of a neighbour, Darcy John Serrell-Watts, whose family had farmed hereabouts for many generations. Fearing that there might be unwelcome strings attached, the gift was vetoed by Darcy John's parents. Then, three years later, the newly-wed Darcy John's mother offered to buy the house as a wedding present, but this time the veto came from the 17-year-old bride. It was not until 1994 that Darcy John and his French third wife, Sylvaine, were finally able to buy Bradwell.

The intermediate owners had been a group of left-wing Turkish dissidents, in whose time the house had been the setting for even more improbable and mysterious goings-on. Apart from bequeathing a very sophisticated and useful security system, the Turks left the house in poor condition, and the Serrell-Watts had much to do to make the house habitable and comfortable - rewiring, clearing rubbish, redecorating, not to mention removing wartime Nissen huts from the lawn. Architect Quinlan Terry was called in to mastermind the architectural aspects, designing an elegant entrance porch on the side elevation and an interpretation of an original cornice that had long since fallen off the house. He also gave authority to their proposal for a Pavlovsk-inspired ochre render for the Georgian wing. The latter initially fell foul of local planners, but with the arrival of a new and unexpectedly helpful English Heritage inspector, John Neale, the pieces at last fell into place. Twenty years on, Bradwell Lodge has matured into such a liveable and loveable house that it is hard to credit the extraordinarily varied history that it has had.