Imagine a TV show presented by an 81-year-old food writer, in which participants compete to see who can bake the best cakes and pastries.
It may sound like a low-key afternoon offering, but "The Great British Bake Off" is the U.K.'s most successful primetime TV show, with young males making up one-fifth of the audience. The 2016 finale was the most-watched TV broadcast (outside of sporting events) in the U.K. in a decade, and the format has been sold to 20 countries.
The competition, which takes place in a giant tent, is fierce but civilized, with contestants offering each other advice and moral support as they wait anxiously for their soufflés to rise. Childish innuendos frequently break up the tension as the talk turns to "soggy bottoms," "doughy balls" and the joy of a "good forking."
But the cozy calm of "The Great British Bake Off" was shattered recently when the show announced it would move away from the ad-free BBC and onto Channel 4, the U.K.'s second-biggest commercial TV station, for its eighth season.
Three of the show's four star presenters—including 81-year-old Mary Berry, who has become a cult figure in the U.K.—immediately proclaimed their loyalty to the BBC and said they would not move with the show to Channel 4.
Only Paul Hollywood will remain. He's the man who tried and failed to bring the format to the U.S. in 2013 with "The American Baking Competition." It lasted just one season on CBS. (But the format has been given a second chance in the U.S., as "The Great American Baking Show," produced by 'Bake Off' creators Love Productions and featuring Ms. Berry, premiered Dec. 1 on ABC.)
Was Channel 4 right to pay $100 million for a judge and a tent? The broadcaster must persuade Brits to embrace new talent and to tolerate commercial breaks, as well as pull in enough advertising and sponsorship to make the investment pay off.
Steve Ackerman, managing director at content company Somethin' Else, which works a lot with the BBC, is optimistic that "The Great British Bake Off" will flourish. "Shows don't live or die by the talent on them," he said. "That's one ingredient. There is a history of hit shows, like 'The X Factor,' that chop and change judges all the time without affecting the ratings. Channel 4 has a strong reputation for developing talent, but ultimately the first few shows will be crucial. They've got to get off to a decent start."
Viewers will inevitably have some hostility when they see their favorite show has been tampered with, but will this prevent brands from getting involved?
Paul Mead, chairman of VCCP Media, thinks not. "From a commercial perspective, 'The Great British Bake Off' is a platform that has been released from its shackles. Whatever they paid, it's a coup for Channel 4. Even with a significant reduction in audience and a new presenting team, it's an incredibly attractive proposition," said Mr. Mead.
Mr. Mead has faith in Channel 4. "It is an innovative business, and they will make a great success of it. I'm super-bullish about it. Look at the potential for extensions: to work with talent, create branded content, extend sponsors into other areas, events, YouTube, the Channel 4 database. It's a winning formula that's open to innovation. They have already got advertisers asking how to get involved. Sponsors wouldn't have to be food related—it could be anyone."
Ben Chesters, managing partner for Starcom and MediaVest in the U.K., estimates that one 30-second spot during "The Great British Bake Off" could cost as much as $187,000. That compares with $125,000 for ITV's "X Factor," which is currently the biggest show on commercial TV.
"Channel 4 is a big draw for young upmarket viewers, and 'Bake Off' conforms to that positioning. Viewers will move in droves, regardless of the fact that there will be ads in the way. Even with a radical drop in audiences, it will be very, very profitable," Mr. Chesters said.
He believes that it's not only the celebrities that make the show, but the contestants too, who come from every walk of life. Students, pensioners, mothers and executives compete, representing a huge range of personalities that charm and frustrate the nation.
For marketers, it's the audience that is so valuable. "Advertisers want to be in appointment-to-view properties," Mr. Mead said. " 'Bake Off' has got a mass appeal that would command a premium. It's not just about the size of the audience, it's the magic of coming together for a shared experience, the quality of attention and the media moment in their week. It's a show that connects the generations," said Mr. Mead.
"It's not just the big numbers," said Mr. Chesters. "It's the shareability and the potential for constant communication in the social space. 'Bake Off' is gold dust for a brand."