Thelonius Monk was an unorthodox American jazz pianist and composer, widely credited with inventing bebop. Pannonica Rothschild was a European aristocrat, born into incredible privilege and wealth.

That the pair became the closest of friends, due to Rothschild's fascination with Monk's musical genius, is an interesting side note in the history of 20th Century jazz.

But is it a fascinating enough fact to flesh out a whole film? Not on the evidence of "The Jazz Baroness".

The documentary was directed by Hannah Rothschild, great-niece of the woman immortalised in numerous jazz compositions as "Nica".

The filmmaker pieces together information about her rebellious relative, a mother-of-five who moved to New York after divorcing her French diplomat husband in 1951 and became patron to various jazz musicians, including Charlie Parker.

Hearing the work of Monk literally changed Nica's life and the pair were inseparable after meeting in 1954. Monk, who suffered from mental illness, spent the last decade of his life living in her New Jersey home and died there in 1982.

Their relationship was clearly complicated — Monk was married to Nellie throughout — but this movie doesn't shed much light on whether they were lovers or not.

Monk's son is interviewed at length and insists that Nica was madly in love with his father. Whether those feelings were reciprocated is unknown but Monk did write "Pannonica" about her.

Rothschild is obviously entranced by her late great-aunt's refusal to live the life expected of her and impressed that she chose instead to mix with black musicians at a time when that was unusual for a woman of her class and colour.

But after watching the film, many will want to know more about Monk and less about Nica.

The former comes across as a very cool lady but one who didn't do too much of note except hang around with musicians whose work she loved, helping them financially and nursing them in ill health.

Helen Mirren provides the voice for Nica, reading out her letters and writings in a crisp and clipped tone.

But Monk remains a mystery and viewers may want to know more about the inspiration behind some of his most famous works, such as 'Round Midnight' and 'Straight, No Chaser'.

But perhaps that's a different movie altogether. This one contains a lot of his wonderful music, which is an absolute delight to hear and incredibly evocative of the 1950s New York era.

It's in stark contrast to Rothschild's monotone narration of the documentary, which manages to convey boredom at some points.

Is she bored by her own movie? She reveals at the end that after researching her great-aunt's story she is still basically unmoved by jazz. It's hardly a ringing endorsement for this disappointing film.

'The Jazz Baroness' is showing at Bermuda Underwater Exploration Institute tomorrow at 1 p.m.