★★★☆☆ In the early 1940s, with the world at war and Europe hopelessly divided, everyone was writing a spy story. Or at least, that's what Operation Mincemeat will have you believe: a true tale of ingenious falsehood, where the boundaries between espionage and paperback fiction begin to blur.

★★★☆☆

In the early 1940s, with the world at war and Europe hopelessly divided, everyone was writing a spy story. Or at least, that’s what Operation Mincemeat will have you believe: a true tale of ingenious falsehood, where the boundaries between espionage and paperback fiction begin to blur. The film recounts a famous episode of Second World War history, when senior British Intelligence officials hatched a plan, cribbed from a contemporary detective novel, to deceive the Führer and make a success of the critical Allied invasion of Sicily in 1943.

To be a writer, very often, is to find yourself in battle with history itself, trying to bend factual details just so slightly to frame a better narrative and more three-dimensional characters. Occasionally, of course, writers just make the whole thing up. Recent forms of creative licence in Netflix’s The Crown so enraged some British conservatives that they asked for a disclaimer to be displayed before each episode, making clear that certain scenes were imagined and not historic fact. So, would Operation Mincemeat, which carries more than a few flirtations with the non-factual, pass The Telegraph test? Is it a faithful enough film to allow us all to be good sports and watch in good faith?

The most charming inventions in Operation Mincemeat concern the fleshing-out of the two male leads. Lieutenant Commander Ewen Montagu (Colin Firth) is presented as a man torn between obligations towards his wife, children and brother, and the greater debt of service he owes to his country. Squadron Leader Charles Cholmondeley is part milquetoast, part eccentric schoolboy and brought to life brilliantly by Matthew Macfadyen: a perfect choice for the blend of vulnerable self-effacement and stubborn will that seems to define Cholmondeley’s character. They unite over their plan, an update of the Haversack Ruse in which a dead corpse will be disguised as a real British agent carrying Top Secret papers and delivered into the hands of Nazi spies. The endgame is a bid for tactical disinformation over the planned invasion of Sicily which will lead Germany to divert troops over to Greece not long before the planned attack.

The film also elevates the role played by one Lieutenant Commander Ian Fleming (Johnny Flynn), weaving in Bond references left, right and centre to suggest that the man behind Dr. No also helped to defeat Hitler. He is found, cigarette in lips, punching away at a typewriter when given a chance, occasionally popping up to marvel at the spy gadgets that will soon deliver 007 from evil. (It’s more than possible that a scene was pulled from the edit, with an enormous clang, in which he orders a martini only to be asked how he likes it served). There is space too for a bitter love triangle to play out between Montagu, Cholmondeley and Jean Leslie (Kelly Macdonald) a widowed secretary who determinedly weaves her way into the planning behind the great ruse. A contrivance that feels wedged into the story with too little grace as an afterthought to the main hook of clever men, being clever.

On the level of pure entertainment, Operation Mincemeat hits its marks well enough. A strong cast makes a success of a script that just-about carries its mixture of romance, intrigue and light comedy. There are also occasions where the film can’t make its mind up about the rotting corpse that lies at the centre of the deception. A few scenes use the deceased as a prop for queasy slapstick humour, but then a second tone of reverence is introduced around the non-consensual sacrifice made by this real-life figure: a homeless person, by the name of Glyndwr Michael, who had committed suicide and was thought to be without any family.

For those who can’t get enough of Second World War spy stories, Operation Mincemeat would make an interesting double-bill alongside the recent Munich: The Edge of War, in which Neville Chamberlain is seen in a more sympathetic light than the diplomatic pushover he is sometimes portrayed as. But the success of that earlier film lies in its internationalism, portraying both English and German sides of the conflict to offer a more rounded portrayal of the fog of war.

There is no similar element of pathos in Operation Mincemeat which can look lightweight by comparison, its bravado enjoyable at times but also too heavily freighted to a one-sided story of triumph that we know too well. It has its moments, but the film is guilty of being fun but forgettable, much like those numerous spy stories cooked up on typewriters in the quiet hours of night and then lost to history when the guns fell silent.

Tom Duggins | @duggins_tom