British TV production in the US. Laurence Olivier's Lear - a commanding, detailed study

''I would say that Larry's is the best Lear I have seen,'' says Michael Elliott, producer of Laurence Olivier's television presentation of the awesome Shakespearean tragedy ''King Lear.'' ''Most Lears evade the part. With him, it is straight down the middle - no tricks, no effects.''

This is Lord Olivier's first appearance in a Shakespeare play filmed exclusively for television. The Granada TV production was seen earlier this month on Britain's Channel 4 and will be given its first public American screening tomorrow (Tuesday) at the Museum of Broadcasting in New York, as part of the ''Britain Salutes New York'' festival. (Last Tuesday it was screened at the White House during a dinner in Olivier's honor given by President and Mrs. Reagan.) Meanwhile, sales efforts are under way, and American viewers will probably be able to see it on broadcast or cable TV before long.

It is eight years since Olivier acted in Shakespeare. His autobiography is a great success in Britain and throughout Europe, and interest in the veteran actor is at a peak.

''Lear'' is a compelling performance, touching and tempestuous, balking at nothing. It is only the second time in an almost 50-year career that Olivier has played the ''foolish fond old man'' who unadvisedly invites and succumbs to the sugared flattery of two callous daughters, giving them his kingdom, and unjustifiably banishing his third daughter, Cordelia, when she refuses to heave her heart into her mouth. He first played Lear on the London stage in 1946. The Times critic called it a ''performance of magnificent ease.''

His television portrayal is also toweringly self-assured, a commanding, detailed study - as good in little as in big things - of a man old before he is wise, whose blunder forces him to follow, almost as if he wanted it, a path of anguish. It is a path from cursing to blessing, from self-blindness to discernment - or, as Michael Elliott conceives it, ''the story of a society passing from one epoch to another, from the rule of a divine tyrant king into a democratic era.''

It is a play on many levels, not least as a vehicle for self-consciously great acting. That it is a play is something that Shakespeare's writing characteristically does not let its audience forget (''O heavens,'' Lear cries, confronted with his diabolical, scheming daughters, ''if you do love old men, . . . Send down and take my part''). This theatricality is something that presents its own problems when Shakespeare is transposed into television.

In this production, a clever balance is struck between the artifice of a stage play and literal naturalism. It was shot entirely in the studio, but considerable chunks of moorland and not a little mud were brought in, and a monumental circle of standing stones like Stonehenge was fabricated.

The primeval atmosphere of 9th-century Britain was intended, an atmosphere also suggested by very effective lighting and a universal mistiness as of ''fen-suck'd fogs'' - but the acting is never overwhelmed by the setting, something harder to control if it had been filmed on location.

''King Lear'' is a tough play. It has even been argued that it is unactable and unstageable. This production, however, makes everything in it look possible, if not inevitable. The ''grand old man'' of British theater casts over the entire proceedings a brittle, crackling magic. The whining of second childhood renders his Lear pitiable. His rages, literally vying with the storm to be heard , are verbal and gestural cataclysms. He curses his appalling older daughters with an apocalyptic petulance.

But the weaknesses of the King are only one side of the character. Olivier also charts, with the adaptability of a superb actor long practiced in his art, Lear's madness and the delicate strength of his final gentle lucidity. Articulate precision is instilled into his entire performance.

It is true, as the director says, that it is not Olivier's way to dodge the difficult; he takes the part head-on. So, in tune with him, does the rest of the magnificent cast. No emotion is played down. As the play pitches to one climax after another, there is always the danger (since good and evil are confronted so overtly) that the whole thing might collapse into the absurdity of melodrama. Olivier's strength has always been that undercutting the conscious exhibitionism of his acting is a scissorlike wit.

Diana Rigg and Dorothy Tutin play the vicious Regan and Goneril as unredeemably vicious. Anna Calder-Marshall is a convincing Cordelia, both vulnerable and definite. Colin Blakely is a tenderly blunt Kent. John Hurt is a troubled and jumpy Fool, prematurely old, who derives no more joy from his wisdom than he does from everyone else's foolishness. Leo McKern provides in his Gloucester the perfect foil to Olivier's King, playing him as a particularly stupid though lovable ancient.

His legitimate son, Edgar, who has to adopt the disguise of ''poor, mad Tom, '' is sympathetically and inexorably played by David Threlfall. (This is the actor who was the unforgettable Smike in the Royal Shakespeare Company's ''Nicholas Nickleby.'') Edgar's ''brother,'' the illegitimate Edmund - that stagy villain - is ingenious and plausible in the hands of Robert Lindsay.

This excellence persists down to the smallest parts in the cast. All the acting (helped, incidentally, by a considerable and powerful use of the close-up) is not merely incisive, but as thorough and unsparing as Olivier's. His ''Lear'' is surely an instant classic.