House owners rewrite history: David Lawson meets a couple who have battled with dry rot and water to restore an architect's dream

Not many people get to change history when buying a home. But David and Kay Smith have done just that with a former council house in the depths of south London. This is not some brick box on a massive estate, however. Tivoli Lodge is a relic of a time when coaches carried genteel parties from central London to one of the capital's forgotten resorts.

Upper Norwood seems the last place tourists would frequent nowadays; modern coaches are more likely to roar through to the nearby National Recreation Centre and giant TV masts. In the 19th century, the great Crystal Palace on this site attracted all the attention. But long before it appeared, another grandiose resort was being created on the neighbouring slopes of Norwood by one of the country's great architects.

Decimus Burton, remembered for his Hyde Park Corner Arch and the Palm House at Kew Gardens, was planning a fairytale wonderland and Regency crescent to rival Regent's Park and Bath. The attraction lay in the rank, sulphurous streams which repulsed locals but were a magnet to visitors. They would wander the glades and 'take the waters' in what became known as Beulah Spa.

The Smiths knew none of this when Tivoli Lodge appeared in agents' windows during their search for a new home.

'It looked like a wreck - and pounds 20,000 more than we could afford,' said Mr Smith. But they could not get their minds off this strange building, with its arched windows and carved roof fringes. It kept cropping up as they searched - and after eventually buying the place, they discovered why.

'We expected to spend money doing it up, but were not prepared for this,' he said. For five years they have struggled to get the house into a reasonable structural condition. 'The surveyor said it was built 'like an engineer's dream', but perhaps he meant an engineer's dream of dampness.' Scaffolding still clings to the walls in the latest attempt to make the roof watertight.

That time has also been a voyage of discovery, however. Hunting through libraries and tapping local memories revealed that this is the only remaining fragment of the grand spa. 'The crescent was never built because the place went bust after attractions like Crystal Palace came along,' said Mr Smith.

The lakes, glades and pavilion, where Strauss once conducted his compositions for dancers, have also disappeared under a council park, houses and a playground. The house, designed to collect the one shilling entrance fee, appears to have survived more through luck than judgement.

Despite being built by such a great architect, no one wanted the building after the spa closed and it went through a chequered history, including long periods of dereliction and neglect. For half a century it was owned by Croydon council, and during the Eighties it had five owners in as many years.

But the real reason emerged not long after they moved in. A mushroom began to grow on the kitchen panelling and was adopted as the house mascot until a dumbstruck visitor asked the Smiths whether they had ever seen dry rot. 'We then had to dismantle the one room we felt would not need any work done,' said Mr Smith. The house was sopping wet, despite having a new damp course.

But sorting this out helped write another piece of history. Digging into the walls and floors revealed that the house has also been the spa's bottling plant. A spring rose under the current patio and was piped into the ground-floor rooms. Huge fireplaces were discovered, probably for sterilising bottles in clouds of steam from boiling vats. Unfortunately, much of this steam had also penetrated the walls and woodwork and a large drain under the floor added to subsequent problems.

The Smiths feel they can cope with all this, but two problems remain about restoring the house to Burton's plans. Firstly, neglect and a fire have removed most of the original fittings, and what is left has been smothered with tacky modern reproductions.

More seriously, historians insist the house was originally thatched. Scouring old journals and junk shops produced several prints which confirmed this view. But the experts appear to have been misled by an early example of estate agent's hyperbole. 'There is no way this could have been a thatched cottage,' said Clive Whitby, an expert on historic roofs, brought in to repair the leaky slates.

The pitch was wrong for thatch, he says, as were the carved wooden surrounds, and Burton would not have specified thatch. He believes the developers may have promoted the resort with pictures of idealised buildings long before the house was built and these have since been accepted as fact.

So the Smiths' efforts will rewrite the history books. But has it been worth five years of effort? The economics are unclear. One valuer told them that Tivoli Lodge was worth only half what they stumped up five years ago. Another set the value at twice the purchase price.

Mr Smith is convinced the experience has been - and will be - worthwhile. One piece of wood discovered when stripping a door frame put the work in perspective. It had sketches drawn on it for the house, and after years of studying Burton, he recognised from the handwriting that they were by the great man himself.

'That bit alone is priceless,' said Mr Smith, who lovingly covered and preserved them in the frame for the next generation of historians to argue about.

(Photographs omitted)