SPOILER ALERT: This article contains spoilers for the season finale of “The Celebrity Traitors U.K.,” now streaming on BBC iPlayer.

It is rare for the most popular show on television to be one of the best. It is rarer for that television show to become such a public spectacle that screenings of its finale fill out bars and clubs across the country. And it is even rarer for the tensions during those screenings, which you could cut with a knife, to be caused by the comedian Alan Carr .

Yet “The Celebrity Traitors U.K.” did just that. The BBC’s first season of a celebrity version of the game — an elaborate, unpredictable internationally-franchised whodunnit — not only matched expectations. It exceeded them.

Celebrity formats are usually there to extend the ongoing popularity of an

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