Where to begin with this fascinating, infuriating, entertaining and perhaps misleading version of the events surrounding the partition of India in 1947.

To say it is heartfelt doesn't help. Gurinder Chadha's family was uprooted from what is now Pakistan by the terrible events of partition, where more than one million people died.

Chadha grew up in Britain among surviving relatives. Her determination to make a film that honours the memory of all who suffered comes through loud and clear, as does her wish to be even-handed.

She could never satisfy everyone. A Pakistani Muslim critic lambasted her for anti-Muslim prejudice; an English critic lambasted her for taking liberties with the truth - which might be true.

I would criticise her for trying to combine a lush and largely sentimental romance between an Indian Muslim girl and a young Hindu boy with the tumultuous events that engulfed Lord Louis Mountbatten in his term as "the last Viceroy of India".

Trying to make an Indian Gone with the Wind with such raw tragedy as background material seems to miss the point. The big story is the big story. Why impose a cliched romance on top of chaos to sugar the pill? Are we not grown-up enough to take it straight?

And yet. Setting the story in the Viceroy's immense house, with Mountbatten (Hugh Bonneville) and his wife Edwina (Gillian Anderson) newly arrived, gleaming, sweating and bursting with goodwill, is a great idea.

Chadha gives us Upstairs Downstairs in the Lutyens palace in Delhi, with a handful of pink folk in the upper rooms - Michael Gambon as Pug (General Ismay), the Viceroy's chief of staff, Simon Williams as Archibald Wavell, the preceding Viceroy - and 500 Indian servants below, a heaving, toiling, turbaned mass of workers, keeping the paths swept and the tiffin hot.

New to the Viceroy's personal service comes Jeet Kumar (Manish Dayal), who's young, bright, brash and in love. We realise once we meet the alluring Aalia Noor (Huma Qureshi), one of Lady Mountbatten's secretaries, that Jeet's arrival is no accident.

This is the girl he is going to marry - except that he is Hindu and she is Muslim and the palace is as riven with sectarian tension as the rest of the country. Her father is played by the great Om Puri, in one of his final appearances before his death last year.

"Dickie" Mountbatten sets out to free India ahead of schedule, pushed by Attlee's Labour government; the strong-minded Edwina tells him not to rush, her accent so posh that the chandeliers quiver.

Tanveer Ghani as Nehru, Denzil Smith as Jinnah and Neeraj Kabi as Mahatma Gandhi soon converge in the Viceroy's meeting rooms to seek compromise. Simon Callow arrives late as Sir Cyril Radcliffe, the man given the impossible task of drawing the partition boundaries.

This last bit is where Chadha may have taken liberties. She relies on a book by former Indian diplomat Narendra Singh Sarila, a junior member of Mountbatten's staff. Sarila contends that Churchill decided two years earlier that partition was necessary to ensure that a newly created Pakistan would become a strong bulwark against the USSR, thus protecting the Middle East oilfields.

In the film, Pug conceals this from Mountbatten, who is enraged when he finds out. The implication is that the bloodbath was less the fault of the Muslims led by Jinnah or the Hindus led by Nehru, than the treachery of Britain.

In The Guardian on March 18, Ian Jack wrote that blaming partition on Churchill, who had been out of power for two years, is a travesty. Jack quotes prominent historians who discount Sarila's book as "wrong-headed". Chadha says finding Sarila's book was her breakthrough when planning the script with her co-writers Paul Mayeda Berges (Chadha's American husband) and Moira Buffini.

Thus, and as ever, audiences need to be careful about taking the film as history. A great deal of what we see here happened, but not all. Chadha's film gives us a feeling for how terrible these events were - and that is worth praising. Just keep a little salt to hand.