The commercials are designed to restore confidence in the £758m dome, which has been widely criticised and lampooned as the pointless pet project of Trade and Industry Secretary Peter Mandelson.

The adverts, commissioned by the New Millennium Experience Company, were made by M&C Saatchi, who ironically did so much for the Conservative Party's fortunes.

Dome, sweet dome

The 60-second commercial to be shown on Christmas Day is the first broadside in a £30m campaign - one of the biggest ever mounted. The aim is to breed excitement and encourage people to put the Dome on a 21st Century "must see" list.

Jeremy Irons...being used to sell the Dome

The first commercial, which is thought to involve a daybreak-to-dusk sequence, will be re-run several times over the Christmas and New Year period.

It uses the slogan: "Imagine the last 1,000 years took place in just one day" and flashes images of the last 10 centuries.

The Dome organisers are also launching a poster campaign at 3,500 sites nationwide using another slogan: "Imagine what we can do tomorrow."

Adverts will run on and off throughout 1999 but more detailed commercials will be rolled out in September when tickets go on sale to the general public.

Cost is unclear

Prices for admission to the Dome - which will include special family and group tickets - are expected to be announced next month.

The New Millennium Experience Company is already planning a giant party in the Dome on 31 December 1999.

But the structure's longer-term future is less clear. It will close at the end of 2000 and several companies, including the Walt Disney Corporation, are said to be interested in buying it and turning it into a permanent theme park.

Lisa Campbell, of Marketing magazine, says £30m - £1.5m of it over Christmas and New Year - is a lot of money to spend on advertising.

She warned: "We will be bombarded over the next few weeks."

The sum is roughly double the amount Camelot spends on advertising every year.