On average, people buy a sofa every five to seven years and spend about three months making the decision. They usually visit up to five shops.
On top of that, the Sofa Workshop company says, they will make at least three visits to the store they eventually buy from. Not an impulse buy, then - people generally take longer making up their minds about the sofa than buying the house it goes in.
"It's a major purchase," says Ashley Grant of the Sofa Workshop, which has 32 stores in the United Kingdom and a mail-order service. For those intending to buy a sofa bed, he advises asking salesmen direct questions about how often it can really be used as a bed, especially if it is intended for a studio flat.
"A lot of them should be used as a bed on only one or two nights a week at best," he cautions. "We sell only one that can't be used every day. The rest have an interior sprung mattress. They can be standard double bed size, 6ft long, or we can custom-build one any size you want."
While most sofa beds are essentially sofas that you can sleep on, the Sorrento, which is made by KA International, based in London, is a bed that can be made into a sofa. It has a full sprung mattress and is the size of a single bed. It is sold with or without back cushions.
It can also be sold with a second bed contained in the drawer underneath, making either a full-size double bed, or two singles. Depending on the fabric, the single costs around pounds 843, the double pounds 861.
Until recently sofa beds were bough for necessity and were notably short on glamour. But their image has been upgraded, and the mechanism for hauling out the base has improved. At least now you've a fair chance of retaining all your fingers.
Sales of sofa beds account for 28 per cent of Sofa Workshop's turnover; around 800 shift a week. The ones sold via mail order come straight from the factory and are slightly cheaper.
Their mail order customers are often first- or second-time home owners, but are well past the futon-in-a-bag stage. Sofa Workshop Direct promise that if you don't like the sofa when it's delivered, or within 10 days of delivery, they'll take it away again without question. And if you're still trying to make up your mind what's going to match the carpet, they'll provide a courtesy sofa to sit on in the meantime, and take it away when the new one arrives.
Prices for the mail order range start at pounds 399, but in stores where custom made sofa beds are ordered (often for taller buyers) they can rise to pounds 2,000. The current best-seller is a trendy Chesterfield shape, but future trends point towards Big Furniture.
"The size of sofas is definitely increasing," says Grant. "Traditionally, sofa beds were compact because it was assumed that people needed the space. Now the demand is for bigger ones, to make best use of the rooms."
Big sofas needn't always mean grumpy delivery men getting stuck in the sitting-room door. Highly Sprung, which screws, glues and dowels in a factory in High Wycombe and has three stores in London, says its sofas can be made with bolt-on arms and split frames if delivery access is restricted. (They also advise measuring the access before ordering.)
"Sofa beds have come a long way," says the firm's Neil Brown, a former advertising man who started selling Chesterfield sofas from his sitting room by way of a profitable extra-curricular activity.
"The mechanisms, which are made in Belgium, are lighter. Fabrics are so much more attractive that people now tend to buy the sofa bed first and then build the rest of the room around it. It is a big statement."
The company sells about 50 sofa beds a week (Batman and Avengers actress Uma Thurman, who is house-hunting in Notting Hill, was spotted browsing in one of the shops a few days ago). They've noticed a shift in buyer trends, too.
"Instead of moving house, people are redecorating, and have new covers made for their sofas."
Highly Sprung (01494 439596); Sofa Workshop Direct (01443 238699 - for stores 01798 343400); KA International, 60 Sloane Avenue, London SW3 (0171-584 7352).
Rest assured: today's sofa-beds offer functionality with style. Top left, the Dublin pounds 449; main picture, Coniston pounds 449; top right, Tashkent pounds 399; all from Sofa Workshop Direct, and bottom left and right, examples from Highly Sprung and KAReuse content