TV REVIEW : A Limited Portrait of a ‘Marriage’ : The edited version of the BBC drama about Vita Sackville-West and Harold Nicolson’s union is a laborious effort.

And now another chapter of PBS and the Censoring Homophobes.

The unlikely catalyst is “Masterpiece Theatre,” the once-grand, now somewhat enfeebled institution that’s wheezing and hobbling through the early ‘90s on a cane. On Sunday (at 10 p.m. on KCET-TV Channel 28, KPBS-TV Channel 15 and KVCR-TV Channel 24), it begins “Portrait of a Marriage,” a grating, laborious three-part BBC adaptation of Nigel Nicolson’s candid book about a stormy interlude in the complex, unconventional marriage of his prominent, homosexual parents, Vita Sackville-West and Harold Nicolson.

PBS is tiptoeing cautiously, still tied in knots by sharp criticism from church and congressional conservatives of its programs with gay and lesbian themes. (“Public broadcasting is using tax dollars to promote homosexuality,” the Rev. Donald Wildmon, America’s self-proclaimed anti-smut crusader, has falsely charged.)

In June, PBS aired a selectively edited (no nudity) version of “The Lost Language of Cranes,” a drama about a gay father who learns that his son is also gay. And it is offering dual versions of “Portrait of a Marriage.” One (the KCET version) is 34 minutes shorter than the original BBC production. Two additional minutes, showing a rape scene and partial nudity, are edited from the second version, which is tailored to more conservative stations.

The BBC production and the thinner PBS version are both an exhausting grind.

Nicolson and Sackville-West were a fascinating British couple: Harold a distinguished writer and diplomat, Vita an acclaimed poet, novelist and gardening authority whose works on that topic are still widely read. Although the Vita/Harold union endured nearly 60 years, “Portrait of a Marriage” covers mainly 1918-1921, the years of Sackville-West’s shattering, volatile affair with her close childhood friend, Violet Trefusis.

Although Harold (David Haig) and Vita (Janet McTeer) appear to reach a mutual understanding about their separate sexual paths, he is tormented by her obsessive, madly passionate affair with “that swine, Violet.” Harold is Vita’s great friend, Violet (Cathryn Harrison) her lover. As part of their “unmentionable” relationship, the two young women sometimes appear publicly as a heterosexual couple, the tall Vita disguised as a man.

Later, Violet also marries, triggering a violent rage in Vita, who at one point carries off her lover and savagely rapes her. In these stunning sequences, the 6-foot-1 McTeer’s Vita is out of control, full of raw, frightening rage, in striking contrast to the docility of her husband.

“God, it’s all so confusing,” Harold says.

“Portrait of a Marriage” is elegantly staged by director Stephen Whittaker, benefiting also from the BBC’s typical meticulous attention to historical detail. And the performances are first rate.

However, this is a group that wearies you, with Vita’s and Harold’s occasional moments of tenderness eclipsed by Vita’s and Violet’s streaks of meanness. Penelope Mortimer’s adaptation is without joy, giving us no one to like or even care about. Not Vita, depicted here as a self-indulgent philanderer and absentee mother who for extended periods abandons her husband and two young sons to feed a powerful sexual lust. Not Harold, in this account a pathetic wimp who cries a lot and constantly begs his wife to leave Violet. Not Violet, who is no more than a larcenous, degenerate, manipulative tart, according to this production.

There are only occasional hints that these are people of letters. Vita is a best-selling author who never writes, a prolific gardener who rarely gardens. Moreover, there is in Violet no trace of what Nigel Nicolson described in his book as the “brilliant, exciting woman” who would go on to become a distinguished novelist in her own right.

Despite controversy pertaining to its content, even the uncut version of “Portrait of a Marriage” is not very titillating or sexy. A little kissing, a little hugging, and that’s it.

The Gay & Lesbian Alliance Against Defamation has criticized the U.S. cuts, claiming that they “distort the history of the real-life relationship” between Vita and Violet, leaving the impression that their affair was a “passing whim.”

Indeed, one of the omissions is a scene establishing the women’s childhood affection and, perhaps, even a latent lesbianism. And even the British version arguably leaves the impression that Vita may have turned to Violet only to spite Harold after he revealed his own homosexuality. Moreover, except for a single line of dialogue, one would not know from “Portrait of a Marriage” that Vita’s affair with Violet was preceded by a lengthy one with another woman. Or that her subsequent lovers would include many women (including Virginia Woolf).

The Gay & Lesbian Alliance Against Defamation has also characterized “Masterpiece Theatre” host Alistair Cooke’s introductions as “homophobic stereotyping.” But that’s hardly the case.

Cooke does blunder once, saying that Harold was homosexual “in a very mild way,” as if being gay were the equivalent of being asthmatic. The rest of his comments, however, provide insight--an ingredient that’s in short supply in “Portrait of a Marriage.”

“Portrait of a Marriage” also will air Tuesday at 10 p.m. on KOCE-TV Channel 50.