Revolution and rebellion are a reliable fixture at the UK’s biggest history festival, but this year there is also some fierce contemporary dissent. The historian Rebecca Rideal has pulled out of the Chalke Valley history festival in protest at the event’s lack of diversity.

The 148 speakers due to appear this year include the TV historian Dan Snow, as well as politicians Chris Patten and Harriet Harman. But only 32 of the 148 speakers are women, and just one is a person of colour: radio presenter Anita Anand, who is appearing with co-author William Dalrymple to discuss their book Koh-i-Noor: The History of the World’s Most Infamous Diamond.

Rideal tweeted on Thursday that she was pulling out “with a heavy heart … I was forced to confront the issue after I saw the programme and the lack of women and people of colour,” she said. “I decided to withdraw because I thought it might shine a greater light on the inequality.”

The historian had been due to appear on Snow’s History Hit podcast, but when she was sent a link to the festival’s list of speakers, “it brought the whole thing into sharp relief”, she said.

Campaigners have also attacked the balance of the Wiltshire-based event, claiming the programme is heavily weighted towards the second world war and the Tudors. Catherine Baker, a lecturer on 20th-century history at Hull University, pointed out that there were three German military veterans due to speak, compared to the single person of colour. The festival, which was founded in 2011, is sponsored by the Daily Mail, though organisers say the sponsor has no influence over programming.

According to James Holland, programme director and co-chair of the festival, the programming reflects demand. He said that Chalke Valley operated on “a shoestring” and had to sell as many tickets as possible in order to fund activities that include outreach to schools in inner-city areas.

“We have subject matter that will attract a Wiltshire audience. If we don’t produce a programme that people want to come along to, then there won’t be a festival,” he said. “As the festival grows over the years, we hope more people will come from a metropolitan audience and then we can have more diverse programming and so less of the talks on world war two and Anne Boleyn.”

The close ties the festival has forged with inner-city schools have helped to inspire a love of history, he continued. “One of the children from a London academy who came along has now become the first pupil at that school to go to Oxford to read history.”

For the historian and festival patron Anthony Beevor, the object of the festival is “to widen and develop interest in history”.

“Because the festival, which is tented and only lasts a week, is so expensive,” Beevor said, “the organisers naturally need huge audiences and that inevitably means a tendency to invite historians who are the best known and bestselling. Not through any fault of the Chalke Valley history festival, the historians on the bestseller lists almost certainly do lack diversity and so too do the TV channels, which tend to be a showcase for white male presenters.”

The festival focuses on the second world war because of the singular nature of that conflict, he continued, citing his experience of audience questions at public events: “The reason why we are still fascinated with the subject in such an extraordinary way is that moral choice is the element in all human drama, and the second world war posed more moral choices than any other period in history.”

The historian Tom Holland, who is due to discuss the legend of King Arthur, echoed Beevor’s analysis, suggesting on Twitter that complaints should be addressed to “publishers and TV commissioners” instead of festival organisers. But the Bafta-winning historian David Olusoga hit back:

“I just think the festival industry has exactly the same responsibility as TV and publishing in reflecting Britain in Britain’s history,” he said.

“But the other David Olusogas need to get on and write those bestselling books,” Holland replied, “maybe even on Henry VIII or Hitler!”

To which Olusoga snapped back: “So black people have let ourselves down, and excluded ourselves from events by not writing the sort of books you feel we should write?”

According to Rideal, the festival is failing in its wider responsibilities: “There is the tendency to assume that black and Asian historians will only write and speak about black and Asian issues and women will only write and speak about women’s issues,” Rideal said. “That simply is not the case. There are wider issues that we write and talk about. As the highest-profile history festival in the UK, I think you need to be aware of that issue, and to do as publishers and broadcasters have and source more diverse speakers. You need to be proactive.”