The £3m deal will see Scully, who has fronted the popular BBC programme alone since Arthur Negus retired 1983, help launch the cyber firm's new valuation service.

Just as on his Sunday night slot, Scully will oversee antiques experts offering their opinions on a range of heirlooms and bric a brac.

Scully shared presenting duties with Arthur Negus until 1983

Unlike the travelling television show, QXL.com will base its valuations on digital photographs of the objects sent via email.

The service, for which the owners will be charged, could help ascertain insurance values or suggest a reserve price should the item be put up for auction.

"I'm looking forward to seeing what hidden treasures are sent for review," said the 56-year-old celebrity, currently filming the 26th series of Antiques Roadshow.

"I know from my long experience that there are many people with antiques and collectibles that could be worth hundreds, thousands or even hundreds of thousands."

The five-year deal will also see the BBC star presenting an antique auction of the day. Other online features will include a collector's club and chat room.

QXL.com, dubbed by some a "cyber car-boot sale", was set up by Financial Times journalist Tim Jackson two years ago.

QXL.com already booming

The 24-hour service was floated on the London stock market on 7 October, netting Jackson a paper fortune of £40m.

BBC star may attract 'silver surfers' to log on

At present the internet is dominated by the young. The booming business may be hoping that Scully will attract older net users - so-called silver surfers.

Scully's BBC show, which tours venues across the country looking for treasures brought along by the public, appeals to a relatively old audience.

The star will take up his duties at QXL.com on 10 November, the day after his BBC contract expires.