And then there was the World, and the vexed and vexing question of Britain’s role in it. The Victorians got a few things wrong here. They assumed the French - dangerous anti-monarchists - were the enemy, when they should have been looking to Germany, where so many of the Queen’s relations were. Not until the Boer War did they think the Empire might possibly one day end. Nor could they conceive of a former colony, America, taking over Britain’s role of international policeman, though they respected its growing commercial power. Ireland was as ever a problem: Gladstone failed to win it home rule in 1886 while Victoria refused to favour it by building a Balmoral equivalent there for royal sojurns. The repercussions continue to this day.

One of the pleasures of this exhibition, curated by Paul Atterbury and Suzanne Fagence Cooper, is that it is not judgmental: it looks at the world through Victorian eyes. For us, the contradictions are clear. How come the same society that produced the high-tech tour de force of the Crystal Palace also housed its parliament in a mock-Tudor palace? Why, when they so admired the elephants and tigers and birds they encountered on their travels, did they shoot as many of them as possible? Why did a British officer, Charles Gordon, help to torch the Chinese Emperor’s exquisite summer palace in Peking over some ambassadorial squabble, and then write: “You can scarcely imagine the beauty and magnificence of the places we burnt. It made one’s heart sore to burn them.”?

It all smacks, curiously, of uncertainty - which is never what we associate with Victorian vim and vigour, but which is what they suffered from greatly. These were not especially easy times. There was always a war or a threat of war somewhere in the Empire, and at home filthy industry was rampant, epidemics of cholera were raging, asylum seekers were pouring in. Things were happening too fast, so the brakes were applied - aesthetically if not technologically. This is what the modernists disliked about the Victorians: that they disavowed their own modernism. The Palace of Westminster was of very advanced construction, but you’d never know. The amazing single span of St. Pancras Station is hidden behind a throwback gothic fantasy of a hotel. Just because they could build the Crystal Palace in six months, doesn’t mean they wanted to do it everywhere. And those who, like the art historian Sir Nikolaus Pevsner, admired William Morris, had to do so by casting him as a modernist despite all evidence to the contrary.

So the Victorians are difficult, contrary people to categorise. And this is why we now recognise them more fully. John Outram, the architect who has designed the exhibition, has done so with a gorgeous palette of Victorian colours, patterns and collages, and characterised the whole show as a journey in a symbolic ship through the Victorian mind. The voyage begins with doors marked First Class and Second Class - you choose - and takes you through zones named “The Royal Family” (including a suggestive sculpture of Lady Godiva that Victoria gave Albert) “Society” (paintings by everyone from Alma Tadema’s classical idealism to Sickert’s realism) , “Nature” (including a stuffed tiger and an equally stuffed extinct Great Auk) , “The World” (which includes booty from the Far East) and “New Technology” (which includes a 1900 motor car and an early X-ray photo).

Outram describes the feel he is recreating as “Hot Britannia”. Hot to the point of being fevered. It is now a truism to remark that there are two sides to the British character: Lion and Unicorn, carnivore and herbivore, punk and pageantry, Whig and Tory. We have become used to them politely taking turns. But in Victoria’s time, they were inextricably intertwined. Perhaps, in our pluralist, gradually more consensual times, we are rediscovering that attitude - call it ambivalent or holistic, as you wish.

The big stumbling-block, however, is the catastrophe that lies between us and them. For the Victorians, the future had a lot of past in it, and the past could be pressed into the service of the future. There was never a clean break. Perhaps there should never have been. But when Maxim invented his gun and was knighted by Victoria for his trouble, that, in effect, was it. The countdown to the Battle of the Somme had already begun.