In London, where space is tight, a spiral staircase can link sitting room to gallery, balcony to patio garden or first floor to a loft conversion bedroom. Despite the drawbacks lots of people still find them attractive.
Tony Capon, whose Cambridge-based company Albion Designs produces about 15 spiral staircases a week for the residential and commercial market, finds it is now being asked to supply to builders planning one as a feature in newly built houses. "The largest number of requests are for loft extensions," Mr Capon says. "Supplied and fitted, the cheapest would cost around pounds 1,200 plus VAT. In ornate cast iron, it would be from pounds 2,500."
Anyone considering giving it a twirl should first consult the local planning department, as staircases are hedged about with specific building regulations. "We do offer advice," Albion says. "But really you should have an architect submit drawings to make sure it complies with all the regulations."
Original Victorian designs have had to be modified as most are too narrow. "You used to be able to pull old spiral staircases out of skips," Mr Capon recalls. "Not any more. We have a collection of designs which were found in skips, but we have had them all copied to new sizes. If you wanted one made to link the back of the house down to the garden, you could pay between pounds 6,000 and pounds 8,000, although some people with large terraces do pay up to pounds 20,000."
Most staircases come in either cast iron, which needs regular maintenance if it's outside and is not to look like the poor old peeling Forth Bridge. But you can paint it in different colours when the mood takes you. A polyester powder coating baked on like car paint lasts longer but you are stuck with the colour, which might chip, but not peel. Albion says colour preferences have altered.
The bright red of a few years ago has vanished along with city brokers' scarlet braces. Cream and white are in now.
If you already own a rusting spiral staircase, DIY restoration is not a Saturday afternoon job. Oxley's Metal Restoration Services, in Chipping Camden, Gloucestershire, can shot-blast the bits and repaint them, from around pounds 800. But you will have to take it to pieces. "They weigh a ton," warns Simon Hudson at Oxley, "but we can come and put it back together for you if you get stuck. It should be fine for another 10 years."
The firm, which also restores steel bicycle frames and cast-iron garden furniture, can supply a new finish in any colour, including bronze, aged gold and old copper.
But maintenance is not really the problem, estate agents say. "Great if you have one on a maisonette on the coast with wonderful views, so you can take advantage of the height without taking up extra square footage," says Stephen King, of Strutt & Parker. "Put one in a country cottage and it can almost devalue the property."
Peter Rawlings, of Foxtons estate agents, agrees. "In a young, trendy two-bedroom apartment, a spiral staircase is a definite advantage," he says. "In a four-bedroom family house it is not. They can be dangerous and awkward for children. They are a good investment in the right atmosphere, say linking a sitting room up to a conservatory. I have seen some wonderfully elegant spiral staircases, but most times they are a pain in the bot."
Albion Designs 01223 836128; Oxley's Restoration Services 01386 840466; Strutt & Parker 0171 823 2899; Foxtons 0171 590 1000