‘The Lost Prince’ is brought to life, royally

“The Lost Prince,” premiering Sunday on PBS’ “Masterpiece Theatre,” tells the largely true story of Prince John -- the epileptic, possibly autistic youngest son of George V, the reluctant king of England during World War I -- who was kept largely from public view and toward the end of his short life lived apart from his family, in a farmhouse on the fringe of their country estate. A BBC co-production, written and directed by Stephen Poliakoff -- a force in British theater, television and film for more than two decades, though not really known here -- it is expertly played, sensitively shot and pretty much a textbook on how to translate history into viable, life-size drama.

It is also, notwithstanding the odd comical scene and a bit of mildly cheery philosophy at the end, almost unbearably sad. And, spread over two nights, it is also very long -- very long and very sad -- and so something of a difficult journey.

Johnnie can’t play ball; can’t spell or draw a straight line, can’t understand the simple intelligence tests his doctors give him -- or doesn’t care to. He goes about in an attitude of cheery dreaminess interrupted by frightening seizures. The doctors recommend “complete isolation,” the queen decrees that “no visitors must be allowed to see him, for their sake, and his,” and henceforth he mainly associates with servants -- which, given the state of his family, is not entirely a bad thing. (His most important relationship, besides that with his loving older brother George, is with his devoted governess, Lalla.)

This is more than the story of an unfortunate boy, however. Covering a period from 1908 to 1919, through World War I and the Russian Revolution, it’s a picture of the twilight of monarchy, a time when Europe was still dominated by crowned heads, most of them related. The ruling families of England, Germany and Russia all shared a common grandmother in Queen Victoria -- the czar (married to Victoria’s granddaughter Alexandra) was Cousin Nicky; the kaiser, her grandson, cousin Willie. (“Masterpiece Theatre” host Russell Baker helpfully points out that the words “kaiser” and “czar” are both forms of “Caesar.”) The tale is told domestically, and largely from a child’s-eye view, glimpsed through doors and from balconies. There is no stock footage of rolling tanks.

Poliakoff does his royal subjects the favor of finding them human, even if not especially cuddly or even always very nice. They are all people trapped by circumstance, unable to be other than they are, victims of their time and class and absurd divine rights. The sterling cast includes Michael Gambon (“The Singing Detective,” “Gosford Park”) as Edward VII, grandfather to the prince; Tom Hollander (“Cambridge Spies”) as George V; Miranda Richardson (“Dance With a Stranger,” “Blackadder”) as Queen Mary; Gina McKee (“Notting Hill”) as Lalla; Daniel Williams and Matthew Thomas as the younger and older Prince John. The early scenes, especially, are full of enlivening, enlightening images -- a huge birthday cake decorated with goldfish bowls, a red carpet being unrolled along a pebbled beach for the family of the visiting czar; George V’s briefly glimpsed tattoos, from his days as a sailor. There is a bit of dramatic tidiness building to Johnnie’s climactic “recital” -- where he shows the family that he has finally learned a thing or two -- and a few occasions where the orchestral score is a little too insistent. But that’s show business, and overall it is an excellent, if draining, work.

*

‘Masterpiece Theatre: The Lost Prince’

Where: KCET

When: 9 to 11 p.m. Sunday

Rating: TV-PG (may be unsuitable for young children)

Matthew Thomas...teenage Prince John

Daniel Williams...younger Johnnie

Gina McKee...Lalla

Miranda Richardson...Queen Mary

Tom Hollander...George V

Michael Gambon...Edward VII

Bibi Andersson...Queen Alexandra

Executive producers Peter Fincham, David Thompson and Joanna Beresford, Rebecca Eaton. Writer-director Stephen Poliakoff.