For more than 30 years, Black History Month has been a fixture in Britain’s cultural calendar, celebrated every October in schools and at tens of thousands of events across the country. But this year the event, which starts on Monday, is at the centre of an appropriation row as campaigners complain that a number of councils have scrapped the name, describing it instead as a celebration of all different ethnicities.

The historian and broadcaster, David Olusoga, is among those who have spoken out to defend the need to keep the month focused on black history. The shadow equalities minister, Dawn Butler, said the Windrush scandal exposed the need to keep black history in sharp focus.

The Conservative-led London borough of Hillingdon, in west London, stopped Black History Month in 2007 and resisted attempts earlier this month to get it reinstated, instead focusing on a programme of multi-ethnic events called Culture Bite with events on south Asia, country dancing and wine tasting.

Wandsworth, the Conservative flagship borough in south London, has similarly reinvented the celebration as “Diversity Month”, and contracted it out to a company called Better which manages Wandsworth’s libraries.

Diversity Month, explains Better’s website, is intended to be a time of “celebrating and learning together about the many and varied experiences and cultures within our borough”. Events feature Indian, Polish, Spanish, Chinese as well as African and Caribbean cultures.

Boroughs such as Hillingdon and Wandsworth are highly diverse. Wandsworth’s 11% Asian population is the same size as its black, African and Caribbean population, according to the 2011 census. Hillingdon’s south Asian population is twice the size of its black population at 21%. Nationally 3.3% of the population is black, African, Caribbean and black British while 7.5% is Asian and Asian British.

Black History Month highlights the contribution of Britain’s high profile figures in the arts and politics, as well as the lives of people like Stephen Lawrence, whose murder triggered nationwide soul-searching about institutional racism.

Olusoga, who contributes to Black History Month talks, said he was disappointed some councils were trying to dilute it.

“I’ve been critical of Black History Month in the past, but I think it really is becoming a shared experience. We can have Black History Month with all people learning about it. Can black people not create things without being seen as exclusive? Black History Month feels to me really inclusive.”

Butler said: “Windrush has highlighted just why Black History Month 2018 is so important. It is important that it remains focused on the contribution of African-Caribbean people. It makes a huge difference to hear black history spoken about positively. But it’s also important that people are reminded of black history.”

Uncertainty about the point of the event has spread to schools. Earlier this week a primary school in Lewisham, south London was challenged by parents after proposing it should be expanded to “My History Month” so every child’s family history could be celebrated. Last year, the head teacher of St Winefride’s Catholic primary school in Newham, east London, apologised after asking parents to send children dressed as slaves in “dirty and worn-out” clothes for a special assembly.

The social commentator Patrick Vernon, who edits Black History Month magazine, said rebrandings of the event were “shameful”.

“Black History Month was established 30 years ago because the black experience in Britain was not recognised in the national curriculum and in mainstream society,” he said. “Unfortunately we do not live in a post-racial Britain. If we did perhaps we would not need Black History Month.”

June Nelson, a Labour councillor in Hillingdon, first tried to get Black History Month reinstated in the borough in 2012 and was rebuffed. Earlier this month she tabled another motion calling for it to be restored, but was once again unsuccessful.

Nelson said there was nothing in the council’s Culture Bite programme that focused on black history. “I feel terribly angry,” she said. “This month should be set aside specifically for black history but there is nothing in there pertaining to the history of black people.

“When I became a councillor in 2010 and it was first brought to my attention they said they did not have the funds for it. I took my eye off the ball for a few years, then when I started making enquiries, I went to a few of the schools and they weren’t doing anything, apart from putting up a few pictures on their noticeboard.”

Nelson, a healthcare assistant who came to the UK from Guyana in 1977, said Black History Month was needed now more than ever, with escalating rightwing rhetoric and growing divisions in society as the UK moves towards Brexit. “I think it’s important that we remember the black people who have contributed to our daily existence, in every aspect.”

A spokesman for Wandsworth council said: “We are proud to celebrate the historical achievements and successes of all the diverse communities that make up our borough and who all contribute so much to life in our city. We do continue to recognise and celebrate Black History Month with a number of specific events but we also at the same time celebrate all the different faiths, ethnicities, cultures and genders of all who live in our borough.”

Hillingdon declined to comment.

Linda Bellos, former leader of Lambeth council who introduced Black History Month to the UK 31 years ago, said: “The involvement of black peoples in all strands of cultural and political life is often omitted and the impression created is that there is little or no positive contribution except within music and sport.

“Black men and women who have played a significant and positive role in the history of Britain are written out of history. This needs to be acknowledged.”

The origins of Black History Month

There was a “negro history week” in 1926 in the United States, but the first Black History Month took place in the 1970s at Kent State University in Ohio.

It took root in the UK in 1987, on the prompting, some say, of Ansel Wong, a Trinidadian activist in London and the head of the ethnic minority unit in the Greater London Council.

According to Linda Bellos, a former leader of Lambeth council who developed the idea, the guest of honour at the launch was Sally Mugabe, the first wife of Robert Mugabe. The events placed historical figures such as the nurse Mary Seacole on a par with Florence Nightingale.

In 2004, the black newspaper New Nation listed Jesus, the Rev Martin Luther King and Malcolm X as the top black icons. The event has drawn criticism from black people that if historical black figures are important then they should be considered year-round, and also that the month becomes about hero worship rather than critical understanding.