Back in the 1990s, when stand-up comedy was hailed as “the new rock ’n’ roll”, Robert Newman and David Baddiel used to perform a sketch entitled “History Today”. The two comedians played elderly historians, slumped in the chairs of a dull, late-night talk show. Each time they attempted to engage in scholarly debate their discussion descended into puerile, playground insults.

It worked because Newman and Baddiel are brilliant comic performers, but also because it was then possible to portray history as the musty domain of grey-haired, grey-suited men, trapped in personal feuds and obsessed with obscure historical controversies. That history and historians could be so lampooned was, in retrospect, a luxurious state of affairs.

Two decades later historians have become unwilling conscripts in toxic culture wars, the focus of online hate and tabloid misinformation, rather than TV satire. What is, and what is not, taught in schools and universities, what appears in our children’s textbooks, how heritage organisations research and present the houses and objects under their care, have all become front-page news.

We are where we are, in large part, because historians have been doing their job. Over recent decades that has led them to turn their analytical gaze towards aspects of Britain’s past that had long been purposefully marginalised – in particular the histories of slavery and empire. The historians now being targeted by journalists and politicians are almost exclusively engaged in those fields of study. Given that politicians, this summer, were willing to pick fights with the star players of the England football team, it is hardly surprising that historians are considered soft targets.

The gradual growth in the study of slavery and colonialism, which began in the 1960s, was a small component within a far bigger revolution in the study of history. Back then a generation of historians that included EP Thompson, Eric Hobsbawm, Dorothy Thompson and Christopher Hill expanded the fields of social history and working class history, which they very often examined from a Marxist standpoint. Their aim was to recover the lives of the poor from what EP Thompson called “the enormous condescension of posterity”.

Twenty-first-century historians seeking to rescue the millions who laboured on the plantations, or who resisted British imperial rule, from similar condescension find themselves in a radically different environment. The study of those specialisms is increasingly portrayed not as an expansion of our national history but as a politicised assault upon it.

Yet rather than challenge the history of the favoured culture-war topic, the tactic is to discredit the historians themselves, the intellectual equivalent to playing the player, not the ball. As the facts of phenomena such as the transatlantic slave trade cannot be refuted, the motives of those who study them are instead called into question. While the historians of the 1960s were denounced for their Marxism, the abuse levelled at today’s historians is of a different order. The aim is not to engage in historical debate but to delegitimise opponents.