Q: Did you enjoy the film?

A: Yes, I did, surprising myself in the process. I knew that it had already provoked considerable controversy: in January 2013, soon after shooting ended, a statement from all three children of Princess Grace of Monaco criticised it for "major historical inaccuracies" and the inclusion of "purely fictional scenes".

Originally scheduled for release in November 2013, it was delayed by disagreements between director Olivier Dahan (La Vie en Rose, 2007) and US distributor Harvey Weinstein. When it finally premiered at the Cannes Film Festival in May 2014, most reviews were tepid or hostile. As a result, I went to see the film in much the same spirit as Rhett Butler joined the Confederate army in Gone With the Wind. Like Rhett, I've "always had a weakness for lost causes, once they're truly lost".

Is Grace of Monaco as bad as most critics thought? I don't believe it is. It features a commanding performance by Nicole Kidman in the title role. Roger Ashton-Griffiths does pretty well as Alfred Hitchcock; Frank Langella is sympathetic as Grace's confidant, Father Francis Tucker, and André Penvern looks reasonably like French president Charles de Gaulle.

There is a series of amusing cameos from Derek Jacobi as professional courtier Count Fernando D'Aillieres. Robert Lindsay is a credibly crude Aristotle Onassis (in the film, as in life, one of Rainier's advisers until their spectacular falling-out in 1963), and Paz Vega plays Maria Callas with some verve. Tim Roth, as Grace's husband Prince Rainier, wears a permanently puzzled look, as if he can't quite work out what he's doing, and only seems ever to stop smoking when he's asleep.

Described in an opening credit as "a fictional account inspired by real events," the film focuses on two main issues: what happened to former Hollywood star Grace Kelly as, six years after her marriage to Prince Rainier, she found herself increasingly discontented with life in Monaco. The second revolves around the simultaneous efforts made by President de Gaulle to subject Monaco to French taxation, which resulted in a French blockade of the principality for several months in 1962–63.

Q: Was the film historically accurate?

A: Given the criticisms of the film's historical accuracy by Princess Grace's children, Prince Albert II of Monaco and his sisters Caroline and Stéphanie, this is an important question (though the fact that their statement was issued before the film was even edited, let alone released, suggests that they may be opposed to any film about their mother).

When the film opens, Grace has already secured the throne for the Grimaldi dynasty (preventing it, under a treaty of 1918, from becoming a French protectorate) by bearing Rainier two children: Caroline in 1957 and Albert in 1958. But she is restless with court ritual, misses her life as a movie actress, and is frustrated by Monégasque aristocracy in her desire to turn charity work to practical effect by opening a new children's hospital. While the sequences used to convey these feelings are indeed "purely fictional," they do suggest emotions that the real Grace herself may plausibly have experienced.

More controversially, there are strong suggestions in the film that all is not well in her marriage: Rainier is always "busy", and they have separate bedrooms. At one point, she shares her dissatisfactions with Father Tucker, who spells out that any divorce would involve the loss of her (now royal) children. We shall never know if there were such tensions in 1962. There were rumours that Rainier began to be unfaithful during Grace's first pregnancy and that, over the years, Grace herself turned to other men. But these were just rumours, and the only people who knew the whole truth are both now dead (Grace after a car accident in 1982, and Rainier in 2005).

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Since Grace, as the heroine of the film, plays a major part in defending Monaco's autonomy against French pressure (a David v Goliath struggle if ever there was one), Monaco itself, in the film's logic, becomes a place worth defending. Is it?

Monaco is a tiny principality, less than a square mile in size, on the southeast coast of France near the Italian border. Ruled for centuries by the Grimaldi family (whose connection with it began in 1297), its main industries in modern times have been perceived to be gambling, banking and tax avoidance.

Since the principality has minimal taxes on business and does not impose income tax, it traditionally functions as a magnet for the very wealthy. The film suggests that Monaco was right to defend its autonomy against French pressure, but de Gaulle's intervention was far from unreasonable. The French president correctly blamed Monaco for making it possible for many French companies and wealthy individuals to evade taxation.

There are two other major sub-plots in the film: Alfred Hitchcock visits Grace in Monaco to try to persuade her to take the lead role in Marnie − an offer she finally refuses. And Rainier's sister Antoinette (Geraldine Somerville) plots to replace him on the throne with her own son. Both of these things did happen, but not during the course of the crisis with France.

Q: What did the film get right?

A: The marriage of Oscar-winning actress Grace Kelly and Prince Rainier of Monaco in 1956 created as much − and perhaps more − interest in the world as that of Prince William and Catherine Middleton. In fairytales, the prince and princess live happily ever after. Grace of Monaco looks beyond the traditional storybook ending to ask: what comes later?

It shows a princess who has little contact with her husband and is concerned about the future of her children. After six years in Monaco, she still does not speak French properly, and she seems to have difficulty knowing how to behave as a royal princess and win the hearts of the people of Monaco.

Yet when Kidman's Grace finally decides to take on and play her own last role − as a princess of the house of Grimaldi − she brings the same dedication to it as the real-life Grace Kelly in the last two decades of her life.

Q. What did it miss?

A: The crucial moment in the film is Grace's speech to the Red Cross Ball in Monaco on 9 October 1962. While Kidman delivers the speech with considerable skill, her message is in essence a defence of "happiness and beauty" against aggression and force. She sounds at one point ("I believe in love") like a hippie in San Francisco in 1967.

At the end of the speech she receives a standing ovation, and US defence secretary Robert S McNamara turns to General de Gaulle and says: "You're not really going to drop a bomb on Princess Grace, are you Charles?" This is wrong on so many counts, the most obvious being that de Gaulle wasn't actually at the ball.

But the film also suggests that Grace's party and speech defused the crisis. In reality, its removal was the result of a compromise tax deal signed between France and Monaco that made French citizens who had lived in Monaco for less than five years, or companies doing more than a quarter of their business outside the principality, subject to French taxation.

If Grace champions happiness and love, Rainier makes it clearer what is really at stake. "The future of Europe is business for the sake of business," he declares at a meeting: governments shouldn't involve themselves in matters of business and finance.

Confidence of this kind in the dictates of the market looks increasingly ironic following the banking crisis of 2008. After years of austerity and the recent work of Thomas Piketty on growing inequality, perhaps the main problem with Grace of Monaco is that, in focusing on the fictional part played by Grace Kelly in the real crisis of 1962/63, it distorts the history of Monaco's struggle to keep the world safe for tax havens.

How many stars (out of 5) would you award the film?

For enjoyment: ***
For historical accuracy: *

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