Demand for second hand convertibles is showing signs of year-round stability here in the UK as hard-top coupe cabriolets gain favour with used car customers, according to a valuation specialist.

Retail customer interest in convertibles has historically risen for summer and fallen away in winter but CAP believes this volatility will reduce as buyers are won over by the weatherproof security offered by the new breed of folding hard-top pioneered here by the Peugeot 206 in 2001 and since emulated by numerous European and, soon, US brands.

The British love affair with convertibles makes the UK second only to Germany as the biggest market for open top cars. Data from the Society of Motor Manufacturers and Traders show that in 2006 they represented 4% of all new registrations compared with 1.5% a decade earlier.

Despite this year's 'wash-out' summer, almost one in three retail used car dealers reported that demand for convertibles remained high.

Now, as the country enters the traditional period for convertible values to slump, CAP is monitoring closely to see if the increasing availability of hard-top cabriolets, with their reassuring sense of protection from the elements, brings stability to the sector.

According to CAP new vehicle data, folding hard tops represent 29% of the entire convertible market today. In 2004 there were 41 convertible model ranges available to UK new car customers, seven of which featured folding metal roofs, representing 17% of the sector. At present there are 55 convertible model ranges available, of which 16 are metal folding - approaching a third of the total sector offering.

CAP Black Book analysis shows that used convertible prices have proved robust this year, despite the twin-pronged pressures of increased volume and poor weather.

When comparing average month-on-month values for the entire sector, the most significant pricing movements have been related to the new plates in March and September. Otherwise, the underlying used values trend for convertibles so far this year has been of stability.

Retail used car dealers confirm the growth in popularity of hard top convertibles, with more than 60% saying their customers prefer them to canvas roof variants. And a quarter of dealers report that demand for convertibles in general is continuing to rise, despite the approach of winter.

CAP forecast manager, Jeff Knight, first predicted the stabilising impact of metal folding roofs on the convertible market last year. He said: "Regardless of build quality, customers perceive canvas roofs as more vulnerable to the winter elements while hard tops remove those concerns.

"We still have to see whether this ingenious but complex metal folding roof technology remains problem-free in the long term. But at the moment, the signs are that these cars are enjoying high consumer demand regardless of the season."