Britain's Black Power movement - and its battle against institutional racism - is in danger of being "written out of history", according to a new book about its principal figurehead, Darcus Howe.

The claim is one of the opening contentions in Darcus Howe: A political biography, in which the authors argue that the major flashpoints of black political activism - such as the trial of the Mangrove Nine, and the Black People's March of 1981 - are being overlooked in favour of a more palatable version of British history.

Writing in their introduction, Robin Bunce and Paul Field argue that "there has been a resurgence of outright denial, linked to a romantic, dumbed-down 'whiggish' view of history that suggests that racism was always someone else's problem."

They add that Britain is consistently portrayed by politicians as being "on the side of the angels" in race relations, and point to the 2007 celebrations of the abolition of the slave trade as an example of how Britain prefers to propagate a myth of itself as "the utopia of civilized fair play".

Fighting  for equal treatment. New Cross Fire 1981

Their book, which is published by Bloomsbury, claims to correct and balance some of that denial by using Darcus Howe's biography as the framework for the first, detailed history of Black Power in Britain. It traces the story from Howe's Trinidadian origins, through his political activism in the 1970s and 80s, his subsequent broadcasting career, and up to his controversial refusal to condemn the London Riots of 2011.

Dr Bunce, Director of Studies for Politics at Homerton College, Cambridge, was moved to research the book a few years ago when Howe was diagnosed with prostate cancer, from which he fortunately recovered. Over the course of two years he met with Howe, who is now 70, once a fortnight, sorting through documents and conducting interviews.

"It occurred to me that Darcus Howe was striving for many of the same things as the Black Power Movement in America, which is obviously much better known," Bunce said. "What nobody has documented is the British struggle. We are now reaching a stage where the people who can tell us about it are not going to be around for much longer."

"One reason that the story is not well-known is that we prefer to tell a story which presents Britain as a place of civilisation and fairness. The effect is that people like Howe, and what they did, are being written out of British history. Sadly, the truth was never as good as we like to think; the history of black people in this country from Windrush until at least the 1970s is one of being treated as second-class citizens."

British Black Power was far less prominent than the American black rights movement, which had a clear political focus in segregation, and produced iconic, internationally-recognisable figures such as Malcolm X and Martin Luther-King. Despite its lower profile, however, it played an critical role in the fight against the less visible problem of institutional racism in the police, the justice system, and the jobs market.

The story of the movement is inextricably tangled up with that of Darcus Howe himself. Born in Trinidad, he originally moved to the UK in 1961 to study law, although he subsequently entered journalism. In 1968, on the advice of his uncle, the Caribbean intellectual, CLR James, he attended the 1968 Montreal Congress of Black Writers, where he met members of the Black Panthers and various West Indian political movements. Stimulated by their views, he then became involved in the 1970 Trinidadian black power revolution.

After returning to London, Howe became a leader of black political activism in the UK. Famously, in 1970, he masterminded a campaign to stop the Metropolitan Police from closing down the Mangrove Restaurant in Notting Hill, a centre of black and celebrity culture in London which was raided 12 times in six months by the force. This climaxed in a pitched battle between police and 250 protesters, following which Howe and eight others - the so-called "Mangrove Nine" were charged with riot, affray and assault.

Fighting for equal treatment 2014. Mark Duggan 'lawfully shot dead' while unarmed

Conducting his own defence over 55 days at the trial, Howe not only secured some measure of acquittal for all the defendants, but forced the judge to acknowledge a level of racial hatred within the Met. "He basically turned it into a trial of the Police," Bunce concludes. "His defence appealed to the Magna Carta, and the media loved it because it was rooted in English traditions of fair play, but was also enormously radical and subversively funny."

Ten years later, Howe was again at the centre of a landmark moment in racial politics in Britain when, after the New Cross Fire, in which 13 young black people died, he organised The Black People's Day of Action, a march across London, protesting against police mishandling of the case. During the 1970s and 80s, he also became a prominent journalist and broadcaster, writing for publications including The Guardian and editing the magazine Race Today, while presenting a series of programmes which covered ethnic minority issues for a general TV audience on Channel 4.

As late as 2011 he remained a controversial public figure, by refusing to condemn the London Riots and instead demanding action on the disproportionate number of young black men who were being targeted by police stop-and-search strategies - a policy which had resulted in the shooting of Mark Duggan and precipitated the unrest.

But even though the urban black poor in Britain remain a marginalised group in society today, Bunce argues that the history of British Black Power should be also be seen as having created real social change, not least in the form of a cultural shift which enabled the equality bills of the 2000s, and the more effective representation of ethnic diversity in the media.

"The vast majority of people in Britain today want a fair and decent society," he added. "The debate now is about how we achieve that. The idea that, for example, there is racism within the police force would have been entirely unacceptable in the 1970s. What Howe and the Black Power Movement achieved is recognition that grass-roots activism and community action can contribute to real change."