For MASTERPIECE fans, waiting for the new vicar on Grantchester is like waiting for Halley's Comet or a Cubs pennant.

It takes patience, but yes, it's worth it.

On July 28 – in the season's third week and fourth episode of Grantchester – Tom Brittney (top), as Will Davenport, finally takes over as the crime-solving vicar in a little English village. He replaces James Norton, who had finished his three-year contract playing Sidney Chambers, and stayed for some transition episodes.

In some ways, it might not seem like a big change. Both stars are tall, handsome and young; Norton is 34, Brittney is 28.

But this is set at a time when a few years seemed like a new generation. "I represent this sort of youth coming in at the end of the '50s – the rock 'n' roll, leather-jacket-wearing, motorbike-riding, Elvis-listening people," Brittney said during the Television Critics Association Press Tour session for the show in February.

Sidney (Norton, left) listened to jazz and rode a bicycle; Will (Brittney) listens to rock and rides a BSA motorcycle.

At first, Brittney says, it was "terrifying. I never, never ever thought I'd be on one .... When you are going 70 miles per hour down a motorway, that does not feel natural. (But) I did start getting the bug for it, and I did start probably going a lot faster than I should have."

There's one other key difference. "James was the sexy vicar," Brittney said. By comparison, Will is – for now, at least – celibate.

That's not a Church of England requirement. "It's a personal thing that happened in his life," he said.

Love is elusive for Will and, until recently, for Sidney – but also for Morse in the Endeavour mysteries. That's wise, said MASTERPIECE chief Rebecca Eaton. "It allows the female viewers to daydream about being the one who would finally win their hearts and make them happy."

Besides, vicars have plenty of other things to worry about. "Especially in the 1950s, they were an integral part of life in a village or town," Brittney said.

And these Grantchester men also keep helping the local cop, Detective Inspector Geordie Keating (Robson Green, right) solve crimes, something Brittney seems to enjoy. "I grew up watching CSI," he said.

He also grew up watching his co-star. Green, 55, had his first regular TV role two years before Brittney was born. In 1995 (when Brittney was 5), Green was coaxed by young producer Simon Cowell to record some songs; three singles reached No. 1 on the British charts.

"He sang them to me all the time on the set," Brittney said.

Their first meeting was imposing, Brittney said. "We grew up watching him in the '90s all the time, and he was a massive singer .... He just came up to me and just gave me a big handshake, 'I'm Robson.'

And I'm, like, 'Yeah, I know. You're TV's Robson Green!' "

–  Masterpiece: Grantchesteris on  PBS, 9 p.m. Sundays (check local listings)