The depigmented areas are most noticeable in dark-skinned people.One 20-year-old sufferer spent his savings on a course of treatment which included a 50g pot of cream which was found to contain tiny amounts of a steroid drug in white soft paraffin.White paraffin, a non-therapeutic carrier agent, costs around pounds 1 for a 225g jar. A tube of the steroid cream, available on prescription only, costs the NHS about pounds 1.50, and a patient the standard prescription charge.. The boardroom of the nascent Empire and Commonwealth Museum in Bristol is dominated by a gigantic oil painting of the Delhi Durbar of 1903, the ceremony by which the Viceroy, Lord Curzon, received the obeisance of the people of India on behalf of the new king, Edward VII. Seated with Lady Curzon in a silver howdah atop an elephant, "a splendid creature," as Philip Mason in The Men Who Ruled India quoted an eyewitness, "covered with silver and gold ... followed by a train of 40 or 50 more magnificent animals, all decked and painted and bedizened with cloth of gold and dazzling frontlet pieces and great hanging ornaments...." All troop along while the city's population stands and watches 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.