It is a striking and provocative painting. Lord Curzon once declared, "There has never been anything so great in the world's history as the British Empire, so great an instrument for the good of humanity", and the Delhi Durbar is that conviction of self-righteousness and triumphal vainglory rendered faithfully in paint. It is quite as epic a work of ideological iconography as anything produced by the Russian or Chinese revolutions. But 94 years on, nearly 50 years after India's independence, one looks at it with incredulity. What can that white man, accompanied on horseback or on other elephants by a few dozen other white men in that teeming crowd of Indians, imagine he is doing? What gave him the temerity to try it on? Why was he not torn limb from limb?
The answer is wrapped up in the mystery of the Empire. The new museum will face the challenge of making some sense of that mystery.
The British Empire, with a few important exceptions such as Rhodesia and Hong Kong, was essentially laid to rest in the mid-1960s, with the granting of independence to the majority of the remaining colonies. Since then it has been a multiply taboo subject. Liberals could only talk about it in terms of a dark and shameful past. Imperialists bemoaned the loss and subsequent national decline. Former subject peoples used it as a rod to beat us. Empire was accordingly something that could not be discussed at all, and one grew up in the aftermath of its disintegration with only the haziest idea of what it had all been about.
My own grandfather, who died in 1947, finished his career as Governor of the Windward and Leeward Islands in the Caribbean. As a child, I found sepia photographs of him buried in drawers, dressed in his governor's uniform, all plumes and medals and starch, gazing out through his gold- rimmed spectacles. The photographs can have been taken no more than 25 years before, but I could imagine no way of relating to them.
Perhaps the new museum will help. Installed in Brunel's original station building at Bristol, the oldest surviving purpose-built railway terminus in the world and itself a marvellous product of mid-Victorian imperial self-confidence, it is so far only a shell. Behind the newly cleaned pseudo- medieval battlements, under the 72ft span of the mock hammerbeam roof of the passenger shed, or in the high vaulted spaces of the undercroft there is as yet almost no hint of what might be done here: it is all potential. But pounds 4m of privately donated money has already been spent on the refurbishment and other preparatory tasks. (Sir Jack Hayward, the property developer, whose hobbies listed in Who's Who include "keeping all things bright, beautiful and British", has given the bulk of the money.) If the application to the Heritage Lottery fund, probably for about twice that amount, is approved, then, within three years of the lottery money being released, Britain will have its first full-scale memorial to the centuries of glory, paternalism and self-satisfaction, of squalor and plunder.
"We're not trying to celebrate the Empire," says Dr Gareth Griffiths, the curator, sitting in the shadow of the Delhi Durbar painting. "The word 'empire' conjures up all sorts of images and emotions, depending on who you speak to - go into the street and ask a dozen people and you'd get a tremendous range of reactions. Those people whose ancestors lived and worked abroad think of it one way, others regard empire as something purely negative and racialist and everyone that's associated with it as jingoistic.
"It's like the Holocaust - both these subjects are extremely emotive, and some people say they are so appalling that there shouldn't be any institution that even addresses them, that you should never mention them whatsoever. I take the view that, yes, there were certainly negative aspects to the 500-year history of the Empire - but there is no point in sweeping any of this history under the carpet because we continue to live with the legacy, and it's important that we present the history of the Empire and allow a debate to take place."
A consensus is building among scholars that a reassessment of the Empire and its significance is overdue, and that now, with the imminent return of Hong Kong to China, and the marking of 50 years of Indian independence in August, a new, less polarised way of thinking about the subject has become possible.
"There is much more interest in the subject now," says Professor Peter Marshall, editor of the Cambridge Illustrated History of the British Empire and one of the new museum's chief scholarly advisers. "Immigrants from the new Commonwealth countries, from the Caribbean and from South Asia, want the British connection to their countries to be talked about - they want their children to be taught about it in school. And while the older generation felt you either had to support or condemn it, the younger generation takes a more relaxed approach. There's also a feeling that to understand Britain you need to understand the Empire, because it's inside us."
Professor John MacKenzie, the museum's other scholarly adviser and author of books such as Propaganda and Empire and Imperialism and Popular Culture, likewise believes we are at an interesting juncture in our relationship to the Empire. "I do think we've reached a stage in the nation's history," he says, "where we have to start moving out of our post-imperial guilt complex. It's odd that Britain has paid so much less attention to its former empire than other European states. But now that's beginning to change."
MacKenzie talks excitedly of the Empire as a "culturally interactive experience" and therefore "particularly amenable to museum treatment". The cliche of Empire is that the British laid down the law and their subjects toed the line. In practice, however, we were as much acted upon as acting: we gave them cricket and football, they gave us polo and lacrosse; Lord Curzon may have wallowed in viceregal glory through the streets of Delhi, but every detail of the Durbar ceremony was Indian.
The British may have transformed India with European ideas about politics, justice and nationhood, but we took, too, and, in the process of taking, we transformed our own cities and possibly ourselves. "If you sit on the top deck of a bus going down Whitehall and go past the Foreign Office," says MacKenzie, "you can see an amazing sculptural representation of the Empire. Our cities are full of pompous buildings and statuary, reflecting the Imperial role. Britain continues to be affected by the experience of India; paradoxically, with distance we are becoming more aware of our interaction with India."
MacKenzie rejects the idea that the museum will not "celebrate" Empire, but insists that it will be a celebration of a very particular type. "There is an element of celebration that you can intrude into the museum: celebration of the sheer capacity of peoples to survive, to maintain their own culture and indeed to develop it, precisely because it's under pressure; for example, the survival of African culture under apartheid. Cultures under pressure are especially creative."
This is a pertinent theme because, as John MacKenzie insists, "this museum is not going to be a top-down view, describing how the British created the largest empire the world has ever seen and portraying the subject peoples merely as being acted upon. Rather it is going to describe how indigenous peoples reacted, survived and changed us, creating new elements of hybrid cultures and in the process changing us in profound ways." He gives the examples of how African art was absorbed into the fabric of Western art early this century; of how gamelan players from Bali turned up at the Paris expo of 1889 and stunned Debussy, thereby helping to change the course of European music.
In this sense, he suggests, the study of Empire, far from being an opportunity to brood or gloat over past glory, will be a way of celebrating "the modern sense of syncretism in culture which interculturalism has produced". Divest Empire of its coercion, oppression and plunder and what do you have left? The fascinating, innocent seeds of the post-modern phantasmagoria in the midst of which we live today. "By celebrating living culture, we hope people from all communities will be lured in. It must be a museum for all communities."
Yet clearly the coercion and the oppression cannot be ignored. Brunel's Great Western Railway, of which the museum's building was the magnificent full stop, was, after all, built by the pitiless toil of tens of thousands of Irish navvies. The wealth of Bristol itself, from which John Cabot sailed 500 years ago and discovered Newfoundland, the first creative event in the Empire's history, was built on the proceeds of a trading tradition which included more than 2,000 slaving voyages. On Christmas Day, 1903, Lord Curzon passed through Delhi in the Durbar in all the dazzling glory of absolute power - but what the painter of that scene could not evoke, and what the witnesses could not forget, was the silence in which he was received; "the crowds, the cavalry, the swaying elephants, the bells, the silver howdah and the cloth of gold," as Philip Mason wrote, "- and silence."