"The Littlest Horse Thieves," a Disney production filmed in England and released there with the lovely, evocative title "The Pit Ponies," might have flourished under the direction of a filmmaker like the late Carol Reed, who excelled at showing the differences in perception and experience that separate a child's apprehension of reality from an adult's. Now at area theaters, "Horse Thieves" is a children's movie that suggests darker, sadder possibilities than the Disney studio is inclined to contemplate.

The setting is a Yorkshire coalmining town in 1909. The new manager at the mine hopes to salvage an unprofitable operation by introducing machinery that will speed the transfer of ore from the coal face to the surface. This automation will eliminate the need for a stable of pit ponies to haul the ore wagons.

Learning of the pending demise of the ponies, three children - the manager's daughter and two boys whose miner father fied in a cave-in and whose mother has remarried, with another miner - conspire to kidnap and shelter the animals. They brave considerable danger but are discovered soon after completing the rescue mission. The plot begins to cave in at this point. The miners, led by the boys' stepfather, go out on strike as a gesture of solidarity with the kids, who still hope to spare the ponies from the glue factory.

Given the mine's economic state, such a gesture is unthinkable, even if the men admired the children's courage and felt vaguely threatened by the ponies' obsolescence. The obvious source of dramatic conflict and poignance is lost - the likelihood that the adults can't afford to satisfy the generous, altruistic impulses of their children. Moreover, there's some recognition of the potential folly of such impulses: Flash, the oldest and ablest of the pit ponies, turns out to be frightened and disoriented on the surface. A lifetime in the mines has also left him blind.

The filmmakers conspire to finesse the disillusion and sorrow that might be experienced by the children in the story and the children in the audience by giving Flash an heroic exit and closing on an absurdly cheerful note. The once indifferent mine owner (the late, great, elegantly acerbic Alastair Sim) is transformed into a beaming sweetums, who invites all the workers home for a picnic and endows the remaining ponies with a pasture all their own.

One couldn't ask for a sunnier fadeout, but it mocks every aspect of the story worth respecting. The class and generational conflicts that might have given the film substance are magically blown away. Lanky, coltih Chloe Franks is the most attractive and responsive of the juveniles, but the most fetching performer of all is the pony who plays Flash. In a better children's movie this sturdy, lively animal might have inspired feelings of tenderness and pathos approaching the mythic.