Yesterday the Tate got round to agreeing. The announcement by its director, Nicholas Serota, and chairman, Dennis Stevenson, that it is to split its British and modern collections and set up initially a temporary - and by 2000 a permanent - museum of modern art in London, seems to have some substantial caveats.
First, the Tate has not yet raised any money for the project. Second, it has not even got a site. Usually two such significant snags would relegate the plan alongside the other pipe dreams that are regularly raised in the arts whenever the word millennium is uttered.
Yet there is general agreement that this project will happen, and swiftly. The Tate, with its successful re-hangs of recent years, has a high reputation in the private sector and already wealthy patrons are said to have promised money for a new modern art museum.
The Henry Moore Foundation, which has millions of pounds, has been having talks. As far as public money is concerned the Government has advised the Tate to apply for funds from the lottery and the millennium fund, both still to be established. One interesting change that seems to have taken place since August, when the Independent first reported the proposed changes, is the thrust of the Tate's thinking.
Then it seemed that dictating the change was Mr Serota's desire that the Tate should house properly as comprehensive a display as possible of British art from the Renaissance to the present day. What to do with the international modern collection (at present a third of the Tate's display) was very much the second priority.
But yesterday's announcement dwelt almost totally on the excitement of a national modern art museum for London, displaying the Tate's Picassos, Rothkos, Warhols and the rest in a new purpose built gallery.
Perhaps the trustees have taken on board the view, sometimes ignored within the inner sanctums of the art world, that the public, as opposed to art historians, go to the Tate to see the contemporary, the wacky, and the bizarre rather than the solid achievements of the not always highly regarded British school.
Perhaps, indeed, the casual visitor likes the juxtaposition of British historical and modern international - walking from a room of pre Raphaelites to a room of Rothko abstracts.
Art historians seem divided over the merits of separating the collections.
Geraldine Prince, of Edinburgh University, says it is out of touch with a climate of greater European cultural harmony to isolate the British collection, while Nigel Llewellyn, of Sussex University and chairman of the Association of Art Historians, says that 'British art has been downplayed. There is so much interest in it at the moment that we must welcome this initiative.'
So what are the immediate problems for the Tate? The first is raising the money. Strangely, in an arts world ever short of funds, this should not be all that difficult.
A new modern art museum fits in nicely with the criteria the Government has announced for its millennium project and with the criteria likely to be announced for lottery proceeds. As it will inevitably be seen as a major international venture, private benefactors from both sides of the Atlantic will want to be associated with it.
The next problem is the site, first for the temporary modern art museum which could be set up as early as 1995, and then for the permanent building. Dennis Stevenson, chairman of the trustees, says that the temporary museum could quite simply be an empty office block.
Since the Independent floated the story in August readers have suggested possible sites including Battersea Power Station and Bankside. Nicholas Serota said yesterday that Battersea Power Station was appealing inasmuch as it was empty, but was not easily accessible by public transport and was expensive to run. Bankside was a possibility, though he did not sound all that enthusiastic, and suggestions of Docklands and Canary Wharf provoked no enthusiasm whatsoever. The site, stressed Mr Serota, must be central and well served by public transport.
And then there is perhaps the most important question. What will be in the new gallery? Are Henry Moore and Francis Bacon part of the history of British art or central insights into developments in international modern art? Serota says that they are both.
They will be treated in depth in the Tate gallery of British Art and also represented in an international context in the new gallery. But if the Henry Moore Foundation gives money to setting up a new modern art gallery it may well want more than a token representation of Moore's works.
As a national museum devoted to modern art the new gallery would be competing directly with the New York Museum of Modern Art, the Guggenheim in New York, the Pompidou Centre and the Musee D'Art Moderne in Paris.
Here a warning note was sounded by David Elliott, head of the Museum of Modern Art in Oxford. He questions whether after years of low government funding and a frozen purchase grant the Tate has bought enough to compete with those institutions.
He said: 'It is an interesting collection but it isn't necessarily of the top quality. There are large holes in it such as European painting and European sculpture of the last 15 years and conceptualism generally.
'But there are of course major strengths such as Picasso, Giacometti and Max Ernst. It is an idiosyncratic collection.'
There is also the problem that the two-way split between British and modern, as defined by Serota, is not how everyone in the field sees the split. David Elliott, for example, thinks in terms of a three way split, British, international modern and then contemporary - the art of the last 20 years. The latter is often very large and difficult to display and constitutes one of the biggest headaches for a new museum.
And what will it look like? Serota hinted yesterday that it would go out to architectural competition. It will almost certainly be a new building, though a Tate spokesman said last night that if there was an exceptional building like the Gare D'Orsay in Paris, a conversion along the French lines would have to be considered. Over to British Rail.