Come on then, what's it worth!

This was only the second year that a Motoring Valuation Day had been hosted by the auctioneer at Bantock House in Wolverhampton. But, after eight hours of hanging about, only a dozen old cars had turned up for appraisal. I arrived after proceedings had been open for an hour, but the only early showing about which Bonhams' Ben Walker enthused was a 1970s British Leyland Sherpa motorhome - unusual, in good nick, but worth £500 under a generous gavel.

Yet, to dismiss the day as a wash-out - the local paper seemingly failed to state which Thursday the event would be on - is to misunderstand the classic car and collectibles auction business. According to Bonhams' Stewart Skilbeck, even casual chats can lead to important lots being consigned. "It's at enthusiast level that we find clients," he says. "Today's a grass-roots event; that's where great things turn up."

Wolverhampton has already proved a gold mine for Skilbeck. "We once had a call from a wealthy local gentleman who had owned a Ferrari 250 GT Lusso from new. It was the late 1980s and, when I first valued the car, I told him it would make £30,000; when we took it in 18 months later, the value had risen to £150,000. We gave it a reserve of £160,000, and sold it for £270,000."

Also, Wolverhampton has a motoring heritage likely to yield lost treasures. Sunbeam cars were made here, as were Turner sports cars, Guy trucks and Meadows engines. In 2004, one local turned up with the 1927 production ledgers from the Sunbeam works.

If you've watched BBC2's The Royle Family, in which the couch-potatoes enjoy The Antiques Roadshow by bawling, "Come on, what's it worth!", at the TV, you can guess the motivation of some visitors to Bonhams' Valuation Day. Brian Fletcher of Albrighton is typical: he says he's not selling his 1972 Alfa Romeo GT1600 Junior... but would not mind Skilbeck's free expertise.

He's happy with his estimate of £9,000, a grand more than he'd had it insured for. So, will it be heading for Bonhams' next sale? "Oh, no!" he says, aghast, "but it's great to know his opinion of the car is the same as mine." As the Alfa roars off, Skilbeck says that it's the sort of vehicle he'd be happy to take bids on. "It's got the three best things: originality, patina and condition."

At the opposite end of the motoring time line is a 1902 Wolseley. The owner, Mike MacNamara, is pleased with Skilbeck's £65,000 estimate. Again, it's not for sale but, after much negotiation, Skilbeck clinches another vehicle, mysteriously referred to as "the steam car" for auction from MacNamara's collection.

And so, the afternoon unfolds, friendly chats leading to numbers being taken and meetings planned. A vintage Rolls, an Aston Martin DB5, an Austin Healey 3000 and some BSA bikes come and go. Local colour comes in the form of a yellow 1972 Jensen Healey. Built in West Bromwich, its owner, Mike Collins, is satisfied at the £5,000 verdict. "I've got no intention of selling it," he says. If, however, it turns up in a forthcoming Bonhams catalogue, we'll understand. He's only human, after all.

For details of Bonhams Valuation Days: 01902 710660; www.bonhams.com