Belle claims to be based on the true story of a mulatto woman born into the British upper class but the film does us no favours when it hides the real heroes of her social struggle.

‘Belle’ opens in Australian cinemas on 8 May.

Gugu Mbatha-Raw plays Dido Elizabeth Murray, an 18th century half-caste woman who comes to inherit both her father’s last name and considerable estate, along with her mother’s good looks. But she must inhabit a world of privilege that cannot decide whether to admit her to their dining parlours or banish her to the service quarters.

However when Dido’s guardian turns out to be the Lord Chief Justice of England, we find her story orbiting a point of law that could result in the bankruptcy of the British slave trade. What follows is a clever interweaving of Dido’s struggle for a place in society, her right to love a young, idealistic law clerk and her witnessing of a crushing blow to slavery.

Belle is a compelling tale but the film plays fast and loose with history. Dido Elizabeth Belle did live at the Mansfield home, but she did not inherit her father’s name or become an heiress. Nor did she marry a law clerk dedicated to abolishing the slave trade—actually, a Frenchman who worked as a gentleman’s steward. And her influence on the Lord Chief Justice is pure speculation. But probably the greatest liberties are those the film takes with the battle against slavery itself.

Belle works hard to put forward a purely rational argument for abolition. Dido’s mythical law-student lover is apparently the son of a clergyman who has come to the conclusion that “… religion need not be the only guardian of our morality”. However contemporary abolitionists William Wilberforce, Elizabeth Heyrick and John Newton strove to eliminate the slave trade because they believed in a Creator who had made all people equal. The strangeness, then, of trying to separate God from the legal system he inspired people to create seems more a reflection of the current antithesis towards religion. In short, Belle makes for a beautiful story, but only half a one.