Architecture: Who will protect us from the protectors?: English Heritage is so powerful that architects are scared to criticise its inconsistencies, says Edmund Soane

It is as if one were writing on the Mafia. 'Our jobs are on the line,' says one well-known architect, explaining why he will not talk to the press. 'These are powerful people I'm talking about. It's too difficult to get work these days, and I don't want to upset anybody.'

Telephone requests for information are met with nervous laughter, followed by prolonged evasion. No one wants to be quoted or named. Yet we are talking about English Heritage, a public body with the benign task of protecting historic buildings. What has it done to cause such fear among English architects?

One of English Heritage's roles is to advise on listed buildings. If you want to alter a listed building, you will need the consent of the local council, which will take - and almost always follow - the advice of English Heritage on the issue.

You can appeal against the council's decision, but English Heritage will then be pitched against you as an expert witness, and you will probably fail. To alter a listed building without consent is a criminal offence. In London, English Heritage has even more power: it, not local councils, decides on applications.

Given the damage done to historic buildings in the recent past, this system might seem reasonable enough, except that it places enormous power in the hands of a not very accountable body. English Heritage's deliberations are private and its officers unelected. Nor are all decisions on historic buildings based on clear, consistent and publicly stated rules; they are only as fair and well-informed as the individual officers making them. While many of its staff may behave reasonably, there is some evidence that not all of them do.

Yet these decisions can have a huge impact on people's lives. You may be prevented from extending your house, and have to move. You may have to spend thousands of pounds on some detail English Heritage thinks essential. You may have to spend your days in an ill-lit room because English Heritage will not allow an enlarged window. You may have to live with some detail or colour you find hideous, or an awkward plan designed for a Victorian family with servants. English Heritage will often have good reasons for such restrictions, but even if they are based on whim, ignorance or pettiness, there is little you can do about it.

To give some actual, but anonymous, examples:

Person A, who wanted to put an oak floor into an ordinary Victorian house, listed on the strength of its facade, not its interior, was turned down and told that oak was an 18th-, not a 19th-century flooring material. He was also refused permission to remove some commonplace fireplaces - the Victorian equivalent of a one- bar electric fire - in what had been the servants' rooms, or to construct an opening between two poky rooms.

An architect received completely opposing arguments from different English Heritage officers. One forbade him to remove an incongruous Edwardian fireplace from a Georgian house, because the fireplace was now part of history; another asked him to return a 17th-century vicarage, much altered in the last century, to its original state.

To make his Queen Anne house more 'authentic', Person B was asked to fit cast-iron gutters, even though the original gutters, made before the invention of cast iron, would have been of lead or wood.

Such whimsical thinking also affects large projects and celebrated architects. Sir Norman Foster is replacing a singularly hideous Sixties lump next to the Tower of London. His scheme will be nine storeys lower than the existing building, rather more elegant, will offer some sheltered public space to an area made inhospitable by traffic, and will open up new views to the Monument and St Paul's Cathedral. It uses stone and rounded edges in deference to the Tower, and follows the lines of the existing streets.

But English Heritage, consulted because of the proximity of the Tower, wanted more: the plan should be broken up into clusters of small blocks, it said, to simulate a historic street plan - even though the site used to be occupied by a monolithic eight-storey warehouse, which, had it survived the Sixties, would now be listed. No doubt, English Heritage's plan would have had an arbitrary charm, but it would have made the building, the headquarters for an insurance company, unworkable.

The Royal Fine Arts Commission disagreed with English Heritage, and Foster's scheme has been given consent. Had English Heritage had its way, however, Foster's clients would have decamped to somewhere more amenable, such as Frankfurt, and the Sixties lump would have continued to disfigure views of the Tower of London.

In less prominent cases, the intervention of English Heritage can stop any work being done at all. Apart from the impositions this puts on individuals, it is not necessarily in the best interests of historic buildings.

In one case, a couple wanted to rebuild an unpleasant Seventies extension to their Victorian house, as well as to restore its main glory, its street facade. Frustrated by the stringency of English Heritage's requirements, which included the preservation of some unremarkable, rotting floorboards, they eventually decided to move. The facade therefore remains unrestored and the Seventies extension still in place.

It is hard to think of another area in which government officials have such power and are obliged to explain themselves so little. Planning decisions that do not involve listed buildings are tested against stated guidelines. But the framework for English Heritage's decisions is vague.

Does it, for example, believe in returning a building to its original design, or preserving the accidents of history that have befallen it? The answer is either, and applicants and their architects can only guess at the line an officer will take.

Particularly absurd is the fact that a building can be listed for a special feature - a porch or even a fireplace - but that every detail, from aluminium patio doors, to Fifties gas fires and lino floors, can then be subject to the taste of English Heritage.

Common sense often prevails in such cases, but sometimes it does not. English Heritage may practise only petty tyranny, but it is still tyranny, and it discredits its good intentions. The Government should limit the powers of this organisation.

The author is an architect in private practice.