Louise (1848-1939) was Queen Victoria’s fourth daughter and the only one to marry a ‘commoner’. She was beautiful, charming and kind, like all princesses should be, and carried out a vast number of royal ‘duties’. Yet all sorts of rumours swirled around her, and when author Lucinda Hawksley began to research her life, she found that the archives were closed.

As a teenager, she allegedly had a baby boy, who was adopted by the son of the queen’s gynaecologist.

There is actually a lot of evidence which points that way, but when his descendant Nick Locock asked for genetic tests, they were refused.

In her early twenties she came under pressure to find a husband and was nudged, unenthusiastically, into a marriage with the Marquess of Lorne. The public thought it was a fairytale romance, but he was probably gay, and they led semi-separate lives. Before and after this marriage she was close to a distinguished Austrian sculptor, Joseph Boehm. (Information about him was also whisked away). When he suddenly collapsed and died in 1890 she was in his studio, and many people believed they had been sharing a bed.

Luckily for her there were no paparazzi in those days. But much as we all love ancient mysteries and scandals, we should not forget that Louise had real qualities.

She was a serious artist and a competent sculptor, although she was never allowed to spend as much time on her work as she wished.

She hung out with Pre-Raphaelites and Bohemians and, living in luxury herself, was genuinely concerned about the poor.

She was deeply involved with the Ladies’ Work Society, which assisted seamstresses, and the National Union for the Higher Education of Women. She believed in female suffrage and Irish home rule.

And although she dutifully raised funds for Boer War charities, she quietly agreed with William Rossetti that it had been ‘a cruel blunder’.

I thoroughly enjoyed this book. It tells us as much as we are ever likely to know about an interesting spirited woman, born into an archaic system which did not change until long after her death.

The Mystery of Princess Louise is published by Chatto and Windus at £25.