Fire offers us the chance to hone a creation more glorious than ever

Clandon Park, near Guildford, can be a difficult house to love. When I used to bicycle over as a child, I found Giacomo Leoni’s double-height Marble Hall somewhat forbidding. Fifty years on, I recognise it as one of the marvels of early18th-century plasterwork and stone carving, with fireplaces by no less a figure than Rysbrack.

But Lord Onslow, whose ancestors built it, remains unconvinced. Since a devastating fire in 2015, he has rejected any suggestion that the National Trust restore it. But the trust has said it will, and I’m with it. Only 40,000 people visited the old Clandon each year – poor for a property near London. The trust has now launched an architectural competition whose results could produce a really exciting fusion of new and old that would attract far greater numbers.

Fire has always been a great scourge of country houses, and in some ways the risks have been worsened by central heating, which dries them out, and woodburning stoves, which get much hotter than conventional grates. Clandon suffered the worst kind of conflagration: it started in the basement, so the whole building was consumed. The thick, brick walls had to be propped up with scaffolding. You might have thought the place was a goner.

Strangely, this isn’t the case. Though the fire took hold with horrible speed, the fire service and staff had 40 minutes to remove the most important items. They were those that were made for the house in the 18th century or were associated with early owners: 600 items that range from Francis Barlow’s giant painting of an ostrich to a lock of George III’s hair. They filled the school that generously played host to them for a couple of weeks.

Alas, a collection of continental porcelain and English furniture, formed in the Twenties, was consumed by the blaze. But as Stoic philosophy tells us, “the Obstacle is the Way” – setbacks are a source of fresh possibility. At a time when appreciation of “brown furniture” is at a nadir, this loss gives the trust the chance to do something different and more appealing.

Far more of the ground floor can be saved than photographs would have led one to suppose. The walls of the Marble Hall still stand. Fragments of the bravura stuccowork ceiling can be pieced together. Today’s craftsmen, using skills honed during the restoration of other fire-struck houses such as Uppark and Windsor Castle, can perform miracles. (They’re not cheap miracles, but Clandon was insured.)

Incredibly, more survives of even the state bed than you’d imagine; there’s a fascinating video on the trust’s website showing the specialist textile conservator Christobel Sambrook brushing down the elaborate needlework of the headboard. Its hangings had just come back from conservation and, still bundled up, were rescued intact. Amazingly, the dining room known as the Speakers’ Parlour – tribute to the three generations of the Onslow family who were Speakers of the House of Commons – was almost unscathed.

Choices will have to be made about the architecture. Since later layers of the house have been burnt away, it would be logical to return the ground floor to its original 1721 layout. After fundraising, the trust might also tackle the lacklustre garden, reviving the Baroque scheme.

However, the bedroom floor of the house has disappeared. While this is regrettable, it gives the trust a glorious opportunity to do something fantastic and new. Gone are the days when doctrinaire modernist architects wanted to sweep away all trace of the past in their pursuit of a utopian ideal.

Having to work around old buildings is, these days, often a spur to creativity. Look at Tate Modern, carved out of the monumental brickwork of a Fifties power station. At King’s Cross, Ben Phillips Architects and the gardener Dan Pearson have created a park inside the shell of one of the iconic gasholders. In 2013, the RIBA Stirling Prize was given to an intervention in a historic building: the Landmark Trust’s Astley Castle, a ruin that has been “reimagined” by Witherford Watson Mann to provide holiday apartments.

It could be that the upper part of Clandon will not only provide exhibition space but also a dazzling three-dimensional adventure, far more engaging than before. I love it already.