Youngsters are also being told that the Roman Emperor Nero married a trans woman, but omits the fact that they probably underwent forced castration, according to research by the Policy Exchange think-tank. However, historic British military victories - such as Waterloo and Trafalgar - are going largely untaught, with as few as one in 10 pupils learning about them, as woke narratives increasingly infiltrate classrooms.

The claim that Stonehenge was built by black people is made in the book "Brilliant Black British History", which is used in schools nationwide. The controversial book, written by Nigerian-born British author Atinuke, states that "Britain was a black country for more than 7,000 years before white people came."

The book is marketed as a "must-have in any school library". However, the Policy Exchange reports that its claim that early Black Britons built the iconic Neolithic stone circle in Wiltshire is "hotly contested and outside mainstream historical thinking", yet "is presented as fact."

The think-tank investigation warns that schools have "taken it too far" as they adapt history curriculums in the wake of Black Lives Matter protests. The think-tank found that George Floyd's death in 2020 led to schools including more material about ethnic minorities in lessons to avoid racism allegations.

The report states that 83% of secondary schools had changed their history curriculum to "decolonise" it. It said: "In some cases this had a positive effect, exposing students to varied and knowledge-rich studies that better cover key areas of British history such as the women's suffrage movement, as well as a wider range of world history.

"However, in too many cases this process has gone too far, leading to the teaching of radical and contested interpretations of the past as fact, or with anecdotes of interesting lives replacing a deeper understanding of the core drivers of history." It continued: "Numerous cases of poor-quality resources being used to teach contested narratives as fact have been identified.

"For example, one book used in classrooms claims black people built Stonehenge, whilst free resources produced by a subject organisation celebrate the genital mutilation of a slave as a form of 'gender transition'." The research also showed that many schools have dropped key elements of British history from the curriculum, with fewer than one in five teaching about the Battle of Agincourt and only 11% including the Battles of Trafalgar and Waterloo.

The report, Lessons from the Past, recommended the creation of a new exam paper on British history from 1066 to 1989 that would be compulsory for all GCSE history pupils. In the report's foreword, historian Lord Roberts wrote: "It is vital that pupils are taught the history of their own nation in a manner that seeks to do more than simply inculcate shame about our past."

Former education secretaries Lord Blunkett and Nadhim Zahawi, as well as Sir Nick Gibb, the former Conservative schools minister, have endorsed the report. Sir Nick said: "Policy Exchange's report rightly identifies that the area where further improvement is needed is at GCSE-level, where increasing specialisation and an over-emphasis on narrow 'theme-related' topics such as health means that too many pupils are never exposed to the full chronological breadth of British history."

Mr Zahawi said: "As a boy who arrived in this great country from Baghdad, I know how important it is that every child in this country - regardless of birth and background - has the opportunity to learn about Britain's inspiring heritage."
A Department for Education spokesman said: "The curriculum and assessment review is considering how to ensure young people have access to a broad and balanced curriculum."