Gavin and Stacey return left Rob Brydon 'flabbergasted'

Rob Brydon is back playing Uncle Bryn

Rob Brydon says he had no clue there were plans for a Gavin and Stacey Christmas special until after the script was written.

The actor, who plays Uncle Bryn in the series, only found out earlier this year ahead of filming in the summer.

The sitcom about a couple who fell in love during a whirlwind romance, will be on TV on Christmas Day, after a nine-year break from screens.

It will focus on festivities at Uncle Bryn's house in Barry.

The show stars Essex boy Gavin, played by Mathew Horne and Barry girl Stacey, played by Joanna Page, who married after that short romance.

Their best friends Smithy and Nessa, played by the show's writers James Corden and Ruth Jones, also struck up an unlikely relationship.

"I think it was February, I had a text from James saying can we have a chat," said Brydon. "I spoke to him and I was totally shocked. I had not an inkling.

Mathew Horne and Joanna Page filmed scenes during the summer as Gavin and Stacey

"I had been asked at every public event is there going to be more? Is there going to be more?

"I said I don't think so, especially given their lives, Ruth with Stella and James in America - so I was flabbergasted."

Corden and Jones got together last year to write the special episode, but the plot is being kept under wraps.

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Speaking to Behnaz Akhgar, sitting in for Eleri Sion on BBC Radio Wales, Jones said: "We had always thought about doing more but we really never had the time to get together to sit down, plan it and actually write it.

Ruth Jones returns as Nessa for the Christmas special

"There are so many actors involved and it just happened to fall into place.

"Last year, we managed to find a weekend where we could get together, work out if there was a story for an episode and then I went back out to the States in February, and we spent a week writing the episode.

"We didn't tell anybody other than our partners because we knew that if we said anything to anybody it could end in disappointment, because we didn't know if we had an episode or not."

• Hear the full interview on BBC Radio Wales from 14:00 GMT and BBC Sounds.