David Tennant came up with the idea for his Rivals character Lord Tony Baddingham to be the father of Emily Atack's character's baby, show bosses have revealed.
In the plot, Sarah Stratton, played by Emily, is heavily pregnant and her Tory MP husband Paul thinks the baby is his. But the audience knows that it is, in fact, the result of a tryst that TV presenter Sarah had with her boss, Lord Tony Baddingham, played by Tennant.
There are many potential candidates, because Sarah has also had affairs with fellow presenter James Vereker (Oliver Chris) and local lothario Rupert Campbell-Black (Alex Hassell).
How the idea came about
Asked how they landed on Tony being the father, executive producer Alexander Lamb said: "At a party, David Tennant said, 'what if Tony was the father?' And we all had a good old laugh about that - and then we started thinking about it.
"It works with the dates, with the times. And we started developing it from there."
Speaking on Rivals: The Official Podcast to Pandora Sykes, Alex said that he and show-runner Dominic Treadwell-Collins liked the cast to get involved with their characters' storylines.
Organic storylines
"I think me and Dominic always talk about what's so fun about working on a long-running drama, is that actually storylines can be organic. You can have a plan and then see something else going on, or a cast member or a crew member can suggest something different. You go, that's a good idea. We should always follow the good idea."
The new episodes have just arrived on Disney+ and show Paul Stratton making the shocking discovery that he's not the father of his wife's baby. He is left reeling after finally learning, from a tearful Sarah, that the baby is the result of her encounter with Lord Baddingham - not least because he's already punched in the face the man he believed to be responsible, and it wasn't him.
Behind the scenes
The podcast also has actor Danny Dyer giving the lowdown on a scene in which his character Freddie Jones runs naked across the grass after nearly being caught with his mistress, Lizzie Vereker (Katherine Parkinson).
"I was all right, because the scene starts off, we're in the bath, we're very warm," he said. "But I did manage to slip my loafers on before I ran through the field."
Katherine laughed: "You were quite grumpy that evening, I remember. It was very cold, wasn't it?"
