Ministers have had a tough time working out who Britain's new trading partners will be after it leaves the EU. At one point it was reported that the British government was hoping to reach out to countries that were once part of the British Empire. The idea is that, now the blood has dried and the dust from the cannonballs settled, the nations of the Commonwealth will be only too happy to jump into a vigorous new age of trade with their former colonial master. Some civil servants doubted this, dubbing the government's plans " Empire 2.0 ".

It all seems so much more appealing than the decline and desperation we face now. Never mind that approximately 35 million Indians died because of famines caused by British misrule, or that Winston Churchill blamed one of these famines on the "beastly" Indians for "breeding like rabbits". Never mind that 5.5 million Africans were taken into slavery and the concentration camp was invented by the British Empire.

It's understandable, in a way. Once upon a time, the sun never set on the lands Britain controlled. Those nostalgic for empire still dream of having the union flag ironed by a Nigerian servant, or getting an Indian boy to make them a nice, cool G&T.

Tharoor laughs when I ask him about Empire 2.0: "Well, Empire 1.0 was a bad idea, to put it mildly. Why would you want a second version?" And yet, to listen to several leading members of the British government and to the fantasies of Britain's great importance conjured up during the Brexit campaign, a second version of the empire is exactly what a lot of people want.

On the same morning these plans for a colonialism reboot were announced, I spoke to Shashi Tharoor, an Indian MP and the author of a new book, Inglorious Empire. The book details the enormous economic damage done to India by the Empire, takes apart the hypocritical notion that some of what the British did in India was for "the good of India", and calls for an end to the monumental ignorance surrounding the subject.

This longing for a return to greatness, combined with a lack of shame, was expressed in characteristic fashion by Boris Johnson when he said that the continent of Africa "may be a blot, but it is not a blot upon our conscience. The problem is not that we were once in charge, but that we are not in charge any more". In September of 2015, David Cameron told the Jamaican parliament that it needed to "move on from the painful legacy of slavery", before announcing his government's plan to build a £25 million prison on the island.

These imperial crimes – and many more – are either not known or glossed over, lost in the tide of colonial nostalgia and the fog of ignorance. During the EU Referendum campaign, the idea of "sovereignty" came to simply mean "making Britain great again", or, in the words of the Brexit camp, "taking back control". The Conservatives' " strong and stable " election mantra has an imperial ring, too, the conjuring up of something old, something dominant, something seaworthy

In the mind of Heather Wheeler, a sitting MP, it's as if, across Britain's former colonies, bright-faced sports fans were punching the air, shouting, "For Queen and country!"

Sentiments like Johnson's were repeated again and again. "Now that's what I call winning!!! Well done Team GB & all our Commonwealth friends, now for Trade agreements," tweeted Conservative MP Heather Wheeler at the end of the Olympics, along with the slogan, "Empire goes for gold".

Much of the public are with her. In January of 2016, a YouGov poll found that 44 percent of Britons (and 57 percent of Conservatives) thought their country's "history of colonialism" was something to be proud of, and 43 percent thought the British Empire was a "good thing".

Nor are we taught about the massacres, the famines, the slave ships and the prisons, or that the Empire was a system of wealth extraction in which the lives of millions of people were disregarded in favour of the greed of the British nation and those who served it. That millions of Africans were forcibly taken to the Caribbean colonies by British slave traders, that the wealth they extracted came at a horrific cost and that while that wealth continues to flow through British society today, its extraction is still keenly felt in the islands of the West Indies. Or that, when it was all done and the British were erratically carving up their empire into new nations, imperial officials attempted to obliterate the truth of what had happened during empire through the systematic destruction and burning of official documents. In Delhi, this destruction went on for so long that the smoke from the fires hung above the Indian capital .

While ignorance is often blamed on individuals, in a sort of, "Just read a book, you dumb bastard" kind of way, Gilroy talks about a manufacturing of ignorance that keeps the people of this country from learning about Britain's imperial past. Schools teach Tudors and Nazis. The man on the street shouts about "One World Cup and two World Wars." We remember the concentration camps of Nazi Germany, as we should, but we are not taught about the British concentration camps of the Boer War, nearly 50 years before.

"The polls didn't surprise me", says Paul Gilroy, author of a number of landmark books on race and empire, "because we're dealing with a politics of almost total ignorance in these matters."

Shame, for Gilroy, is far preferable to guilt because it can be catalysing – a stimulus to action. "Guilt is useless, counterproductive and usually just a source of resentment," he tells me. "Shame, on the other hand, is an appropriate response that can turn people towards the possibilities of redress and reparation."

This guilt is paralysing. Paul Gilroy points out that Freud associates guilt with melancholia, which the psychoanalyst described as a shameless condition, one that relates to the passing of something that cannot be fully understood and thus does not lead to positive change. Melancholia is related to mourning – the loss of empire is painful but it cannot be processed because, as Gilroy says, "Britain might learn too many uncomfortable truths about its history if it was known and considered".

"Guilt is useless, counterproductive and usually just a source of resentment. Shame, on the other hand, can turn people towards the possibilities of redress and reparation."

When a conversation about the British Empire does happen, it is so often defensive or triumphalist. Niall Ferguson, a man who wrote a book called _Civilization: The Six Killer Apps of Western Power – _yes, he means "apps", like on a phone – has sold more books on empire than any other recent British author. He is, as Shashi Tharoor puts it, a "booster for empire". His sophisticated flag-waving comforts readers who don't seem to be able to handle the idea that the country they are from is not 100 percent awesome.

In September of last year, a drinks consortium planned to open a "high-end rum bar" called Plantation. It wasn't until Black Activists Against Cuts stepped in and pointed out that plantations were "places where people suffered and died, where Africans suffered unimaginable violence and terror at the hands of their slave masters" that it was renamed Burlock.

This gung-ho attitude to empire has spread much further than the corridors of power. Its legacy is still all around us.

Such a response in Britain seems unlikely to happen, partly because many Brits do not know about – or refuse to accept – the darkness of empire. Last year, Conservative MP Liam Fox tweeted that Britain "is one of the few countries in the European Union that does not need to bury its 20th century history". Post-Brexit, Fox is now a cabinet minister, in charge of international trade – hardly the place you want an empire booster.

In Warsaw, in 1970, then German chancellor Willy Brandt joined a commemoration to the Jewish victims of the Warsaw Ghetto, dropping to his knees in an act of humility and penance. As a socialist, Brandt had been an enemy of Nazi Germany and had been imprisoned for his political activity. He bore no personal responsibility for that government's crimes, but he recognised that as his country's leading representative, he could do something, and that, as he wrote in his autobiography, he was, "Carrying the burden of the millions who were murdered."

There is already a Plantation Bar and Grill, though. It sells "unbelievable American soul food" and features "distressed wood". It has a "Philosophy" section on its website. It's in Wigan.

In another fitting piece of colonial nostalgia, the East India Company rides again as a seller of "exquisite loose teas and rich coffees; artisan sweet and savoury biscuits; a luxurious chocolate range; vintage and exotic jams, marmalades and mustards…" Their website is foggy about the mass slavery needed for the company to function during the colonial era, or the devastating famines it created by exporting crops rather than feeding people.

"A common complaint from students is, 'Why do we never learn about black history?' And I have to tell them that there isn't much of an option to teach this on the curriculum."

In 1948, the British Nationality Act established the principle of "Civis Britannicus Sum": that anyone born in the empire had the rights of British citizenship. As a result, former subjects of the British Empire came to the motherland as supposedly equal citizens. In response to the racism faced by Britain's former colonial subjects, the phrase "We are here because you were there" became a striking anti-racist slogan.

This remains largely untaught in most British schools – something history teachers across the country discuss. "In my view, there is a woeful lack of engagement on this topic across the curriculum in British schools, considering its importance to both British and world history," says William Bowles, head of History at St Mary Magdalene Academy in north London. "A common complaint from students is, 'Why do we never learn about black history?' And I have to tell them that there isn't much of an option to teach this on the curriculum."

To challenge this lack of public education, Jeremy Corbyn has said that the British Empire should be taught in schools, and various alternative groups are setting out to raise the public's awareness of Britain's colonial legacy. Organiser Elsie Bryant tells me that her project, "British Empire State of Mind", will take a nuanced approach and "help provide some context for what's going on in the world today, in terms of global inequality, poverty and how Britain helped create the conditions that caused and continue to perpetuate it now".

Projects like these are important, not just for the history lesson, but as a tool to understand Britain's current economic and political situation. Post-colonial British governments have shown a fondness for playing the white saviour in countries which need to be "saved", offering "aid" and "development". But it's not an accident that Britain is wealthy compared to its former colonies. The trade, natural resources and labour that could be gleaned from Britain's colonies turned it into a rich nation. At the beginning of the 18th century, India's share of the world economy was 23 percent. By the time the British left, it was a little over 3 percent. The money taxed, looted and traded out of India was used to fund the industrial revolution and the transformation of Britain into the world's pre-eminent imperial power.

Some of the ill-gotten gains of empire even came from a massive compensation package – £16 to £17 billion in today's money, or 40 percent of all government expenditure in 1834 – paid, after the abolition of slavery, to slave owners (slaves were given nothing). As UCL's Legacies of British Slave-ownership project discovered, around 46,000 individual claims and awards were made to those who "either owned slaves or benefitted indirectly from ownership".