We sat around a long, carved wooden table, gazed over by several  generations of worthies, and pondered the truly big issues. Could period paint  increase the value of your house? And, most importantly, how do you get  someone else to pay? 

I was at a one-day renovation course for owners of period property held by  Renaissance, a historical architectural consultants based in Bath, at the  ornate Bishop's Palace in Wells, Somerset. It is now the custom of these  courses, which have been going for four years that they are held in a building  of historic importance. Fair enough, one would hardly take a renovation  course in a Portakabin. But while the course may sound terribly frou-frou, it  actually has lots of valuable hard-nosed information, courtesy of Adrian  Dobinson, a Renaissance senior partner and key speaker, who has a growing  reputation in television punditry as 'the House-Doctor': saviour of heritage  homes and combative scourge of planners. 

Who attends? Well, Dobinson has hosted faded aristocrats hoping to find  ways to care for their teetering piles. But a more significant tendency, he  says, is the 'new aristocracy' and those amateur conservationists who have  bought a heritage house and want to know how to be good caretaker-owners.  I took my pew with about 10 other students, most female between 30 and  50, and most house-owners. Ann Jenkins had come all the way from Rutland  to find the best way to look after her farmhouse, so old that it was  mentioned in Domesday Book. "It's been a pub, a shop and now it's a home,"  she said. Ros Pope, from Devon, was looking for tips for a flat in an ex-brewery. Margaret Cosgrave, from Kent, was doing up an old,  timber-framed, ex-carpenter's shop: "I saw the course advertised and thought,  I might need this." Karen Davies, of Devon, who "has always been  interested in old buildings", did up holiday homes. Another couple has a  glorious Georgian house in Cambridgeshire they were rescuing from  decrepitude. But we all rapidly established that, as owners, we were mere  incumbents, a blip in our houses' histories. 

"You are, as William Morris put it, tenants in time," said Dobinson.  "Whatever you do to it is reversible, or should be." As the guardians of our  shared heritage, Dobinson believes that listed homeowners necessarily have  curtailed freedoms: "Any building protected by the State restricts the owner's  rights." 

Indeed, Dobinson has noticed that some house-buyers are actively  put off by the potential of meddling officialdom, outweighing the cachet of  living in a listed home. 

On average, however, the market price of a building  increased ahead of an unlisted building. And those who love to live in a slice  of heritage should not only learn how to maintain it, but also how to head  off the various bullies; mortgagers, council planners, the local letter-writing  taste police; who all reckon they know best. Dobinson is a seasoned  campaigner, and his gist is empowerment. "Make a good argument," he  insists. "Invoke provenance." In other words; if you can argue historical  accuracy for having a lilac exterior, he says, you have more or less won the  case. For period punters, sadly, the problems might even start before the  purchase. Dobinson rails against the surveyors foisted on us by mortgage  providers, who, even though the buyers pay, often work incompetently and  in conditions of secrecy. "Ninety per cent of surveyors misdiagnose," he  says. "It is particularly galling when mortgage money is retained, as  retention's are often wrong with a listed building." But again, when you come  back to the building society with your historical/conservation reasons against  retention, it often reneges. 

Typically, unnecessary demands for  chemical treatments such as damp proofing. "I have surveyed more than 300  old-houses and only one had rising damp," said Dobinson. "More  damage is done by the chemicals than any damp, if it existed in the first  place." The most common remedy is the removal of the earth from the side  of the house, so there is a step up to the house. Rising damp, however, is  usually caused by a broken pipe underground, a different matter entirely, he  says. Surveyors can be headed off by undertaking a feasibility study of your  own: a type of cover-all-angles survey which is becoming more popular,  particularly for unusual historic properties, such as factories, churches and  follies, that are beyond the scope of the lender, says Dobinson. "A study will  minimise those 'unknowns' that everyone thinks occur with building work. In  fact, there shouldn't be any 'unknowns' at all." Ah yes, builders. "Don't let  them take things away," he warns. "Don't trust word of mouth. Make a  schedule. Forget walk-through quotes. Choose with price but also aptitude in  mind." 

The latter is important, he says, because old houses need a different  building philosophy. "It's the long-term incremental build-up of pipes and  wires that increase damage. Plumbing, electricity, even telephone wires can  cause damage and erosion, as can new materials such as cement, rather than  lime." We are warned not to 'overspecify'. In keeping with his  low-intervention philosophy, Dobinson feels that central heating and  air-conditioning should be carefully considered. "And get rid of old water  tanks, they weigh an old ceiling down." 

Insurance has become a problem for the period homeowner, particularly as  the salvage boom has ensured that doors, staircases and fireplaces are  highly nickable. "Sadly, insurers of historic houses demand a bit more," said  Dobinson. But conventional alarms can destroy period charm, and historic  homeowners may have to splash out on hidden alarms and trip lights. Make  a  record, he counsels. "Before you start renovating, take photographs of all  fittings, special marks and all." After all, buyers appreciate the old stuff.  "Doors, after fireplaces, are the second most important thing in a room for  a  buyer," said Dobinson, who also believes in using the right paint. "Nothing  improves the value of your property faster than the appropriate colour."  Indeed, he believes the feeling that prospective buyers get when viewing a  property of there being something wrong but can't put their finger on it is  often down to colour; ubiquitous white in particular. "A shame, as Britain  has  a long tradition of rich and deep colours." 

Those who have got older houses will realise that there is a certain  amount  of public money for their renovation. "Difficult to get hold of at  the moment," sighed Dobinson. But the single most important way of  softening the blow of period renovation is VAT reliefs, technically available  to the owners of listed buildings and "severely underclaimed". Of about  £500million that should return to listed buildings, only £70million is clawed  back. This is due, he thinks, to the Government's obfuscatory booklet on  the  subject and the fact that there is no application form.

So Renaissance  has published an application formula itself. After all, the custodians of the  nation's heritage, being charged with such responsibility, should be in line for  a perk or two.  I am sure we all left the Bishop's Palace a little bit more confident.