Alec Guinness brings a deft twinkle to G.K. Chesterton’s venerable saintly sleuth “Father Brown” in his only big screen outing as the Catholic crime solver, titled “The Detective” when it showed in the United States.

And while I can’t say with certainty that this 1954 British classic is the most faithful to Christian apologist Chesterton’s vision of a priest who solves crimes and tries to keep the coppers at bay as he tries to “save” the criminals, it does feel like one of the definitive takes on the character.

There’d been one earlier film of Chesterston’s crime solving creature of habits, and there have been several TV and radio series based on the “Father Brown” stories. But what other Father Brown got so into the part and so swayed by the man’s humanity, Christian piety, charity and forgiveness that he converted to Catholicism?

“Kind Hearts and Coronets” and “School for Scoundrels” director Robert Hamer, co-screenwriter Thelma Schneed and the cast get a lighthearted, faintly mysterious and fun film out of Chesterston’s oft-filmed first-ever Father Brown short story, “The Blue Cross.”

Father Brown is soft-spoken in the pulpit, ensuring that “He that maketh haste to be rich shall not go unpunished” (Jeremiah) plays to every parishioner, not just the burglar he interrupted and convinced to go the straight and narrow the night before.

Of course, as he was returning the man’s ill-gotten pounds sterling to the safe he’d cracked, Father Brown was arrested and spent the night in a cell. But once all that was cleared up, without the priest ratting out the thief despite the irritation of the cops and the church hierarchy, a little lecture seems in order.

“I’m disappointed in you, Bert,” he offers. “Firstly, because you did wrong. Secondly, because you did wrong in the wrong way. Frankly, you are an incompetent thief.”

We’re tossed into Father Brown’s world, in which most police don’t know of his amateur sleuthing, which his bishop (Cecil Parker) barely tolerates, a priest preaching to a full house in a modest old church in which no Sunday would be complete without his own personal Kato — a local tough – jumping him afterwards, giving him a weekly wrestling-for-your-life workout.

But the Church is lending out the one “priceless” relic housed in Father Brown’s parish, a cross owned by St. Augustine, to a Catholic convocation elsewhere in Europe. The police have gotten wind of plans by a notorious master thief named Guy Flambeau to snatch it.

Father Brown is merely warned of this, and told to leave guarding the cross to the authorities. But he preps several packages, only one of which holds The True Cross, to tote with him by train and ferry all the way to his destination.

Father Brown, wearing spectacles and wide-eyed with curiosity, must consider every fellow passenger, even ones from the sea of clergy making this pilgrimage with him, a suspect. See how he trips up James Bond’s future boss (Bernard Lee), a jolly chap who passes himself off as a Jaguar salesman.

The British carmarker, the non-driver Father Brown notes with a raised-eyebrow, “made a mistake” by equipping current models with “a single downdraft carburetor.” Only a con artist, or a cop traveling in disguise, would miss the fact that Jaguars were using twin “horizontal” (side-draft) carbs in the early ’50s.

Then there’s the helpful fellow priest who picks up on Brown’s concerns aboit his parcel and urge to ditch those tailing him. “A danger shared is a danger halved,” his fellow Bible-quoting Catholic clergyman intones.

Naturally, he’s the real thief, played by a bearded future Oscar winner (like Guinness himself) Peter Finch.

So this is to be one of THOSE sorts of mysteries, with the thief and the his pursuer meeting, bantering, matching wits and wrestling skills as crimes are considered and carried out. The twist here is that Father Brown isn’t interested in an arrest.

“I want you on behalf of a higher power.”

Guinness is so delightful in the title role that had this been a modern production, he might have been urged to sacrifice half his career to “franchise” the character.

Finch is properly sinister, but also amusing in various disguises. Joan Greenswood is the lone female presence of note, a widowed rich parishioner who becomes “bait” to trap our thief. And Lee and Parker play varying degrees of befuddlement as characters trying to track and rein in a priest who won’t stay in his lane.

A standout comic scene is an auction meant to smoke out our master criminal, with bit player Lance Maraschal hilariously embodying the British idea of a boorish, wealthy “Texan” — then and forever. Watch auctioneer Noel Howlett instantly convert the drawling blowhard’s Yankee dollar bids to “pounds sterling,” then “guineas” as the duel between our Texan and an Anglofile Indian (Marne Maitland) turns teasingly testy.

It’s always delightful to stumble across that rare Guinness comic outing you haven’t seen, and while “The Detective” is no “Kind Hearts and Coronets,” “The Ladykillers,” “Lavender Hill Mob” or even “The Horse’s Mouth,” it showcases him in fine form in a role that would change his spiritual life and inform many of his serene, considered and cerebral performances to come.

Rating: TV-PG

Cast: Alec Guinness, Joan Greenswood, Peter Finch, Bernard Lee and Cecil Parker.

Credits: Directed by Robert Hamer, scripted by Thelma Schneed and Robert Hamer, based on the Father Brown stories by G.K. Chesterton. A Columbia release on Tubi, Amazon, etc.

Running time: 1:26