The trouble with the English, remarked Salman Rushdie in typically apt fashion, is that they don’t know their history, because so much of it happened overseas. And so the island status that motivated Britain’s imperial story in the first place has helped us distance ourselves from all aspects of that story.

There is the way, for instance, that the empire was built and sustained. From the Norman conquest of Ireland in the 12th century, the English began imagining themselves as the new Romans, persuading themselves they were as duty-bound to civilise “backward” tribes as they were destined to exploit their resources, land and labour.

There is the way the empire ended – a gentlemanly release, far less violent and disruptive than the dissolution of France’s dominions, or so the self-congratulatory theory goes. “There is only one empire where, without external pressure or weariness at the burden of ruling, the ruling people has voluntarily surrendered its hegemony over subject peoples and has given them their freedom,” said Clement Attlee in 1960, neatly summarising this belief.

It’s an ingenious and uniquely British perspective, which achieves the seemingly impossible – casting Britain’s empire as a great moral achievement, and its collapse as an act of casual generosity, without any hint at the irreconcilability of the two. The British empire was won, as the historian John Seeley famously claimed, “in a fit of absence of mind”, and given away in a fit of collective indifference.

Lost in all this are inconvenient facts too numerous to list in anything other than the most cursory way. There are the centuries of state-sanctioned criminal activity: the remarkable looting by supposed heroes such as Francis Drake, one of the most notorious pirates in history, and Robert Clive, who pillaged Bengal to great personal gain. There are the crimes against humanity: the innovation of concentration camps in the Boer war that inspired the Nazis, for example, and the cultural annihilation of kingdoms and palaces from Ashanti to Beijing.

Facebook Twitter Pinterest David Adjaye, architect of Britain’s planned Holocaust museum in London. Photograph: Balkis Press/ABACA/PA Images

There is the industrial-scale exploitation of natural resources, enriching the imperial motherland to the same extent they underdeveloped wealth from the colonies, as Walter Rodney pointed out. And then there’s the slave trade that was enthusiastically embraced by Brits of all classes and backgrounds – the greatest manmade human calamity of all time.

Our preferred solution to this inconvenient truth has been to avoid dwelling on slavery and focus instead on celebrating its abolition. At least Britain’s role in the slave trade is remembered in the excellent museum in Liverpool. But having a couple of slavery-focused museums – there is Wilberforce House in Hull, too – sets the issue apart from the mainstream of British history. It’s like a physical version of Black History Month, forcing forgotten histories into the open – a good thing – but as a footnote, a segregated narrative.

We no longer live in a society where the descendants of the colonisers are the sole authors

Few British people understand how fundamental this trade was to the British empire, and the extent to which the history of empire is the history of Britain. That there is not a single museum dedicated to empire, the historical episode with the most profound consequences for modern British identity, is nothing short of remarkable.

The announcement of a new Holocaust museum, designed by the renowned British-Ghanaian architect David Adjaye, illustrates the crucial role museums can play in shaping understanding of the past and present. This museum, dedicated to “the complexity of the Holocaust story, including the British context ... a series of layers that have become hidden by time”, will – quite rightly – take pride of place in Westminster, on the bank of the Thames next to the Houses of Parliament.

Both the fact of the new museum’s existence and its location serve, as Peter Bazalgette, chair of the UK Holocaust Memorial Foundation, has said, “as a statement of our values and a constant reminder of the British connection to this history, much of which we can be proud, but also a reminder of where we fell short, with tragic consequences”.

This is needed now more than ever. Why do we not afford the history of empire the same attention and symbolic value? We are not alone in neglecting it. America only gained its first ever federally funded museum of African-American History and Culture in 2016, also designed by Adjaye, who has described it as the defining project of his career. It’s astonishing that only now does the nation have a museum dedicated to the devastating history of its African-American community – on whose backs, there is a gradual but growing recognition, it was built.

Facebook Twitter Pinterest ‘View of Calcutta from the Esplanade’, c1860, during the period of East India Company rule. Illustration from The History of the Indian Mutiny, by Charles Ball, Volume II, The London Printing & Publishing Co. Photograph: Print Collector/Getty Images

Neither Adjaye nor any other celebrated architect has been asked to build a museum to Britain’s history of empire. The only such place to have existed in my lifetime was a privately operated museum in Bristol, which closed in 2008 to relocate to London, never to surface again.

This national neglect of our imperial past has attracted some strange bedfellows. A pro-Brexit historian recently told me that one of the consequences of Britain’s fatally flawed attempt to integrate more closely with the continent is an academic obsession with European history. He argued that the heads of history at eminent universities have been Germanists, and school curriculums have been obsessed with events in 20th-century Europe. We began to reimagine our history as solely continental, and not the global – and colonial – past it undoubtedly was.

Empire shaped the world. There is an abyss at the heart of dishonest history textbooks | Moni Mohsin Read more

But this is not a history that is universally ignored. We no longer live in an age where people accept the official version of events, nor in a society where the descendants of the colonisers are the sole authors of the story. Indeed, the personal history of Barack Obama – whose father was tortured by the British during the Mau Mau uprising in Kenya – offered some awkward truths from the other perspective.

To counter the historians who have sold us, and continue to propagate, a glorious version of the imperial past, we have a generation of brilliant scholars such as David Olusoga, whose book Black and British paints an accessible picture of forgotten links with Africa and the Caribbean with richness and depth. We have charismatic global stars such as the Indian MP, diplomat and author Shashi Tharoor, whose Oxford Union speech on the impact of colonial rule in India has had more than 4m hits. There is a “Crimes of Britain” Twitter account – whose provocative emblem is a bleeding poppy, its black centre featuring the image of a bone-white skull – that sends out a daily stream of indictments: from British army massacres in Ireland to the devastation of Bengal, and the reduction of modern-day Libya to rubble, it seeks to present an alternative view of imperial legacy.

It may be distasteful to some, but as long as the establishment continues to avoid acknowledging this history, it will flourish underground. That has consequences not just for people like me – Britons personally connected to the events we continue to ignore – it denies all of us an education about the most salient episode in our past. A museum is the least we could do.

• Afua Hirsch is a writer and broadcaster. Her book Brit(ish) will be published in 2018