Impact surprised Broadchurch cast
David Tennant has said the cast of TV hit Broadchurch was taken by surprise when it became a "national talking point".
The whodunnit drama wowed more than nine million viewers last year as fans tuned in every week to find out who killed Danny Latimer.
The murder-mystery returns in January - but Tennant said it was "always written as a one-off".
In an interview with The Observer Magazine, the former Doctor Who star said: "Broadchurch. Why Broadchurch, again? It was never the intention to do it more than once.
"It was always written as a one-off. And we actors were all contracted as a one-off: there was no sense it was going to go again.
"We were taken mildly by surprise when it became a national talking point like that."
Tennant said series two is "absolutely propelled by series one".
Meanwhile, the US version of Broadchurch is not being renewed for a second series.
It was remade in the US, with original star Tennant, after its huge success on ITV.
Breaking Bad actress Anna Gunn took on the part of Detective Ellie Miller, played by Olivia Colman in the original, while Tennant retained his starring role.
But, according to TV Line, the Fox remake will not get a second instalment after disappointing ratings, falling from 4.8 million viewers at the launch of the first series to four million by the end.
The second ITV series, with veteran star Charlotte Rampling among the cast as well as Tennant and Colman, returns in January.
Jodie Whittaker and Andrew Buchan, who play victim Danny's parents Beth and Mark Latimer, will also return to their roles, alongside Arthur Darvill as local vicar Paul Coates.