Lord Falconer of Thoroton, the Minister of State at the Cabinet Office, succeeds Peter Mandelson as the Government's sole shareholder for the project in Greenwich.
Chris Smith, the Secretary of State for Culture, Media and Sport, will continue to answer questions on the Dome in theCommons. He was barred from a long-term role because of a possible conflict of interests. He is also chairman of the Millennium Commission, which gives lottery money to the Dome.
But there were fresh Conservative accusations of "cronyism" over the appointment of Lord Falconer, 47, who once shared a flat with Mr Blair in the 1970s, when both were young barristers in London.
Charlie Falconer gave up a legal practice worth a reputed pounds 500,000 a year to take up a life peerage and become Solicitor-General in the new Labour Government in May 1997, before moving to the Cabinet Office. Lord Falconer has emerged as the "eyes and ears" of the Prime Minister on 14 Cabinet sub-committees. By handing him responsibility for the Dome Mr Blair is underlining the trust he has in his judgement. "He relies on Charlie quite a lot. He seems to rely on him like he relied on Peter Mandelson," said one minister.
But John Redwood, the Conservative spokesman on trade and industry, said: "This is another example of promotion for Tony's cronies."
Peter Ainsworth, the Tory spokesman on culture, condemned the appointment as "yet another example of the cronyism that pervades this Government". He added: "In what way is Lord Falconer qualified to take on the task, other than the fact that he is a close friend of Tony Blair?" Taking charge of the Dome could prove a poisoned chalice, however. Mr Redwood said Lord Falconer could take the blame if it proved a failure while Mr Blair would take the credit if it succeeded.
Whitehall sources said yesterday that the Dome no longer needs a high- profile figure in the Cabinet to promote it. Now that its contents have largely been decided, what is needed is a highly trusted, behind-the-scenes fixer to iron out problems.
Yesterday Lord Falconer declined to be interviewed. As shareholder, he has to ensure the New Millennium Experience Company meets the Government's objectives for theproject, due to open on New Year's Eve. He is also in charge of appointments to the board, their pay, and that of the staff.
Meanwhile, the Tories will demand a statement next week from Stephen Byers, the new Trade and Industry Secretary, on reports that his predecessor, Mr Mandelson, overruled civil servants who warned that he would have had a conflict of interests by remaining in charge of the Dome while also taking important decisions on some of the Dome's financial backers, such as British Airways.