Black history is a series of missing chapters from British history. I'm trying to put those bits back in.

The refusal to accept that the black presence in Britain has a long and deep history is not just a symptom of racism, it is a form of racism. It is part of a rearguard and increasingly unsustainable defence of a fantasy monochrome version of British history.

Very occasionally, I wish I was French. The fantasy usually materialises just after a holiday, when I dream of living by the warmth of the Mediterranean, or after a trip to Paris during which I indulge fantasies of being a Left Bank cafe-bohemian.

The history of the British empire, the chapter of our national story that would have explained to my classmates why a child born in Nigeria was sat among them, was similarly missing from the curriculum.

Our national history cannot be national if, in the near future, one in three young adults feels their stories remain untold, if this country's long global history of empire and interconnections is marginalised and if the historical reality of race is rendered almost invisible.

When historians write the last pages of their books, and the producers of history documentaries sit down to edit the final minutes of their programmes, there is often a strong urge to look to the future and emphasise the positive.

What needs to be debated is whether IQ tests, as currently designed, are fit for purpose, and capable of measuring the changing nature of intelligence in the 21st century among generations brought up with digital technology and different learning habits.

My view as a historian is that the empire was an extractive, exploitative, racist and violent institution and that the history of empire is one we need to confront and come to terms with, rather than celebrate.

Whether we like it or not, there are moments in history when pessimism is the appropriate response.