A document submitted to the Commons Culture, Media and Sport Select Committee inquiry into the pounds 750m project, intended to be the year-long centrepiece of Britain's celebration of the past 1,000 years - and presumably the next 1,000 - discloses that it will contain ... theme park rides.
The 11-page paper from Imagination, the design consultancy hired originally by the Government to advise on the exhibition, explains how its plan for 12 "Time Zones" arranged like a clockface around the structure, each representing a different subject, was suddenly rejected. "Instead of the 12 Time Zones the new company [the organising body, New Millennium Experience] issued a completely new brief ... the new company asked that the Dome contain six 'hot spots' (akin to theme park rides) and other exhibits ..."
The Imagination submission says that visitors, rather than spending a full day at the dome, would now be on "timed tickets and spend only half a day at the site" - for a likely ticket price disclosed by Peter Mandelson, the Government minister in charge of the project, of around pounds 20 per adult. Tickets will cost a similar amount to those for Alton Towers which, of course, is a theme park in Staffordshire. But visitors to Alton Towers can spend the whole day enjoying the rides, rather than having to choose the morning or afternoon.
Imagination tells how its time concept was designed to tie in with the end of the millennium. The emphasis was on education and information, as well as entertainment. But under the new brief drawn up under the aegis of the then deputy prime minister, Michael Heseltine, in February, that all changed. Rather than the exhibition being the main attraction it was relegated to the sidelines - or, as Imagination puts it, to the perimeter area - with centre-stage going to Millennium Show devised by the West End impresario, Sir Cameron Mackintosh.
Since taking over the project, Mr Mandelson is understood to have embraced the new plan wholeheartedly. Mr Heseltine, as a member of the Millennium Commission, is still involved. Imagination, which was paid pounds 7.6m of public money for its 18 months' work, said it could not continue to advise "since the fundamentals of the project had changed so radically it was not possible or appropriate to produce detailed content design".
To be fair to Mr Mandelson - and before he complains - Imagination ends its sharply-worded submission to the committee by saying: "Although not what we originally envisaged, the exhibition will undoubtedly prove a great success and Imagination is proud to have played its part in realising the Millennium Commission's aspirations."
The consultancy, with turnover last year of pounds 50m, is the largest of its kind in Europe, advising major organisations such as the BBC, BT, Ford and Guinness. A spokeswoman stressed that after all its costs and suppliers' fees were paid from the pounds 7.6m of public money it earned from the Dome, the agency's actual profit was closer to pounds 1m.
Last week, the New Millennium Experience Company announced a list of design consultancies which will now be responsible for the inside of the Dome. They will be paid a total of pounds 30m and will begin installing their ideas next autumn.
A spokesman for New Millennium Experience said Imagination's proposal envisaged up to 100,000 people on site at one time. Under the new scheme, a maximum of 35,000 people would be admitted. With 12,000 people watching Sir Cameron's show, that will leave 23,000 roaming the site. Nevertheless, he predicted there would be no long queues for what he called the "large- scale attractions".
The New Millennium Experience spokesman offered the following breakdown of the pounds 750m cost of the project: pounds 50m on a national educational programme starting next month; pounds 200m on site clearance, infrastructure and building the dome; pounds 200m on as yet unspecified content; and total running costs of pounds 300m. He said the search for private sector backing, headed by US sports mogul Mark McCormack, was going "very well".