Back in 2004 Tom Selleck made a TV-movie called “Ike: Countdown to D-Day,” in which, during the days preceding Operation Overlord on June 6, 1944, the Supreme Allied Commander was shown receiving unstinting support for the invasion plan from bulldog British Prime Minister Winston Churchill (Ian Mune), despite expressions of uncertainty from other quarters (especially General De Gaulle). Roughly the same time frame is covered in Jonathan Teplitzky’s “Churchill,” but from the PM’s perspective, with Eisenhower reduced to a secondary role, and the interpretation could not be more different. The stalwart allies of Robert Harmon’s telefilm (the beginning, incidentally, of the director’s long association with Selleck) have become bickering foes, with Churchill (Brian Cox), haunted by the memories of the disastrous Gallipoli campaign on the Anatolian coast he’d been instrumental in crafting back in 1915, frantically arguing that Overlord was far too dangerous and must be called off, while Eisenhower (John Slattery) and Field Marshal Montgomery (Julian Wadham) contend that it has to go forward as planned—and overrule him.

This is certainly an unusual portrayal of the Prime Minister who, however much he might have been distressed at the thought of Overlord’s human cost, is not described in any sources as objecting to the D-Day plan—or having the sort of nervous breakdown depicted here. “Churchill” was written by a historian named Alex von Tunzelmann, but anyone who waits through the final credits crawl will note this admonition at the very end: “Whilst this film is inspired by actual events, its central plot and certain characters have been created and/or fictionalized, and are not to be viewed as factually accurate. Constructed dialogue and other significant fictional elements have been used for dramatic purposes.” This is certainly a very broad disclaimer, and in the present case the breadth is entirely appropriate: this is a highly speculative example of historical revisionism, one in which fidelity to fact is secondary to other considerations—namely, presenting the 69-year old PM as a lion in winter, unable to accept the fact that his time is passing and his glory days waning, even as he is tortured by past mistakes.

In other words, the crisis of confidence Churchill suffers here is pure invention, and innumerable other aspects of Tunzelmann’s script are also fashioned for dramatic effect, often very crudely. The worst is the introduction of Helen Garrett (Ella Purnell), a fictitious young secretary who’s just come onto Churchill’s staff and idolizes him, only to become the object of his wrath. The plot thread reaches its nadir in a maudlin moment in the last act regarding her fiancé, who’s part of the invasion force. But the movie is rife with such cornball moments, like one where three young kids playing soldier encounter Churchill’s car on a country road, and they exchange…well, you’ll just have to see it for yourself and try to stifle a groan or a chuckle when you do, especially when composer Lorne Balfe lays on the moody strings so heavily.

This is, it must also be noted, a small film despite the huge historical context. Confined largely to interiors that are often smoke-filled (though some of the locations are quite ornate), the picture lacks scope, with only some coastal sequences at the start and finish—where Churchill languidly walks—to break the visual monotony. The scale is modest even when Churchill visits Montgomery’s troops before the invasion; we’re told that most of them have already embarked to explain why there are only ten or fifteen of them. Given the limitations, however, Chris Roope’s production design is elegant (despite a surfeit of wall signs pointing the way to bomb shelters—perhaps an attempt by set decorator Neesh Ruben to impose a period feel), and David Higgs’s cinematography equally so. Bart Cariss’ costumes are also spot-on.

So if one is willing to grant the filmmakers plenty of dramatic license and leeway in view of their modest budget, there is much to admire in Cox’s performance as a driven Churchill approaching the point of a complete breakdown. With the help of makeup, the physical resemblance is striking, but it’s the actor’s voice and demeanor that most impress. By comparison Slattery’s Eisenhower is pretty bland, though Wadham makes a convincing Montgomery. Miranda Richardson is the very image of stiff-upper-lip propriety as Clementine, Winston’s long-suffering but supportive wife, who barely misses a beat when he husband suddenly trashes their dining room, in a scene that’s all too familiar. James Purefoy makes the most of his two scenes as King George VI, who despite “The King’s Speech” still struggles with his speech impediment. (The second scene, incidentally, in which he forbids Churchill to sail with the invading force, has an actual historical basis.)

While they differ wildly in their presentation of events, “Churchill” and “Ike” do share one unfortunate characteristic. In Harmon’s movie, Selleck’s Eisenhower is shown in scene after scene gloomily contemplating how Overlord will go, puffing on cigarette after cigarette. Cox’s Churchill similarly broods interminably over the operation’s prospects for failure. The only difference is that he’s cloaked in cigar smoke. Cox is the better actor, but despite all his grimaces he’s no more able to invest these tedious sequences with dramatic urgency than the taciturn Selleck was, particularly because Teplitzky and editor Chris Gill prefer to take things very slowly.

Perhaps the strangest aspect of “Churchill” is that in addition to her more conventional historical work, Tunzelmann has specialized—in a column for The Guardian that spawned one of her books—in satirizing the absurdities found in many movies supposedly based on history. Perhaps her goal in penning this script was deliberately to raise the hackles of Churchill scholars. Whether or not that was the case, she has contrived a provocative portrait of the great man less based on history than imagination and abounding in cinematic cliché, but showcasing a virtuoso performance by Cox.