THE PRINCE WHO WAS KEPT IN THE DARK.

Byline: David Kronke TV Critic

`MASTERPIECE Theatre'' launches its 34th season - and its first without a corporate underwriter, which therefore means it could be its last - with a metaphorically resonant saga: ``The Lost Prince,'' the story of a misunderstood royal taken criminally for granted, only to die prematurely.

PBS' crown jewel has been sorrily undervalued; if viewers and sponsors are as blithe in their benign neglect as King George V and Queen Mary are depicted as being toward their son John, one of the few American series that routinely aspires to greatness (even if it relies heavily on British TV producers to do so) may be buried as tragically as Johnny will be next week.

Set in the early 20th century, ``The Lost Prince'' concerns an unexpected casualty of war: Prince John (Matthew Thomas; with Daniel Williams playing the character as a child), whose epilepsy and learning disabilities (at a time when such maladies were sorely misinterpreted) were considered so inconvenient that the young man was spirited away from public consumption for much of his life - and ghettoized during World War I.

His only champions were his brother George (Brock Everitt-Elwick playing the child and later Rollo Weeks) - the film seems to squander an opportunity by not presenting this resonant story from his more keenly insightful yet equally poignant point of view - and his nanny Lalla (Gina McKee), his fiercest protector, though it seems whenever she's momentarily distracted, quite bad things ensue.

Writer/director Stephen Poliakoff gives his project a stately - a polite way to say somewhat slow - pace, though matters pick up considerably in next week's installment. Much of the cast seems a British who's who - Miranda Richardson stars as Queen Mary, who ignores her son with the same insouciant grace with which she ignores the women protesting on behalf of the suffragette movement, while Michael Gambon plays John's good-humored grandfather.

Scene-stealer Bill Nighy (``Love Actually,'' ``State of Play'') gives a richly droll turn as Lord Stamfordham, whose subservience to both the king and his sons cannot disguise his intellectual superiority. Next week, he offers an important rule of diplomacy: ``You don't declare war while everyone's away on holiday.''

David Kronke, [phone]

david.kronke(at)dailynews.com

THE LOST PRINCE - Three stars

What: ``Masterpiece Theatre'' miniseries about a young royal tragically neglected during World War I.

Where: KCET.

When: 9 tonight and Oct. 24.

In a nutshell: Deliberately paced but fascinating.

CAPTION(S):

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Photo:

(color) England's young Prince John (Daniel Williams, left) counts his brother, Prince George (Brock Everitt-Elwick), among his few protectors in ``The Lost Prince,'' on PBS.