The King’s Man: The best entry yet in the secret agent pastiche franchise

After the so-so Kingsman: The Secret Service and the unendurable Kingsman: The Golden Circle, one might reasonably assume that Matthew Vaughn had nowhere else to go with the secret agent pastiche. This everything-but-the-kitchen-sink prequel deflates such pessimism in disreputably enjoyable fashion.

The new film is involved in genre-fictional genealogy, moving up the family tree from James Bond to the early 20th-century romps of John Buchan and H Rider Haggard. Vaughn and Karl Gajdusek, his cowriter, make sure to undercut the imperialism, but the politics of the thing are still almost as barmy as its relationship with historical truth.

We begin in South Africa – stamping ground of both Haggard and Buchan – with Lord Orlando Oxford (Ralph Fiennes) seeing his wife shot dead in crossfire during the Boer war. He vows that he will keep his son Conrad (Harris Dickinson) out of all conflict, but that resolve is tested as, a decade and a bit later, a sinister cabal manoeuvres the planet towards world war. The film really gets going with the line: "It is time for us to kill Grigori Rasputin! " (Good luck with that.) It transpires that His Grace is now a sort of quasi-independent secret agent who, working with his maid (Gemma Arterton) and an African factotum (Djimon Hounsou), is eager to save Europe from self-immolation.

We have space for just a sketch of the drunken political undercurrents. Lord Oxford retreated from formal involvement with the imperial project when he realised it was an exercise in epic larceny. The illustrations of British repression are not always in the best taste – "These concentration camps are why we're winning the war," someone says as we pan past emaciated Boers – but it is commendable that they made the effort. Elsewhere, however, the film makes a brave hero of George V and casts the key villain as a sort of demented Scottish nationalist. Leninists will be even less happy with The King's Man than will reactionary imperialists. The black servant still takes a bullet for his white boss.

Think too hard about it and you'll give yourself a headache. Happily, the action is so slick and the cast so committed it is easy to push all that to one side and wallow in the imaginative absurdity. Fiennes is charming. Arterton is a hoot. Who could not give themselves over to a scene in which, as Rasputin, Rhys Ifans – the film's lethal secret weapon – duels balletically with the heroes to the strains of the 1812 overture? Time, perhaps, to say "we've seen it all" and close off a weird year. Best Kingsman yet.

Released on December 26th