A Gavin and Stacey star has revealed how Sonia was ‘kept a secret from the cast’ as the crew went to extreme lengths to keep her return hidden.

Gavin’s almost bride-to-be Sonia, played by Laura Aikman, left viewers shocked when she ‘came back to ruin Christmas’ during this year’s special.

Her bridesmaid Anna, played by Lauren Cornelius, has now detailed how the plot was kept underwraps, with nothing being given away until the first read through.

Speaking in an interview with The Mirror, she explained: ‘We never met Laura until filming, she was secret, she was in different hotels and not allowed to be part of anything. She didn’t exist, her name wasn’t on anything.

‘Hearing the story for the first time because none of us were sent the script, we didn’t know anything, everything was revealed at the first read through.

Lauren’s own character was also kept secret until the last minute with her being given several names throughout the audition process.

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A Gavin and Stacey star has revealed how Sonia was ‘kept a secret from the cast’ as the crew went to extreme lengths to keep her return hidden

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Sonia’s bridesmaid Anna, played by Lauren Cornelius (right), has now detailed how the plot was kept underwraps, with nothing being given away until the first read through

The actress added: ‘It was Katie first, then it was Leticia, and then it was Anna. It was totally wild, it was surreal in itself, it was absolutely incredible.

After the show aired, Laura took to Instagram to share the adorable moment her parents discovered she was returning to the sitcom as Sonia while watching the finale.

Her appearance came as a shock to the nation, as Laura had been ‘hidden away’ in a separate hotel during filming, and she had signed an NDA preventing her from revealing she was returning.

As 12.5 million viewers gasped in shock at the big reveal, no one was more dumbfounded than her beloved parents – who had no clue she was making her big comeback.

Alongside the clip, she wrote: ‘The moment my family realise Sonia is ruining Christmas again…’

Gavin And Stacey director Christine Gernon also took to Instagram after the finale aired to reveal the extent of the extreme measures taken to her comeback secret under wraps.

Sharing a snap of Laura alongside Alison Steadman, who portrays Pam in the BBC show, the director quipped: ‘@lauraikman spent the whole g&s shoot being hidden away.

‘Staying in a different hotel, not allowed to come to wrap or screening parties so no one knew Sonia was back. Such a great reveal. And she’s amazing as both actor and person.’

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Speaking in an interview with The Mirror , she explained: ‘We never met Laura until filming, she was secret, she was in different hotels and not allowed to be part of anything. She didn’t exist’

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Her appearance came as a shock to the nation, as Laura had been ‘hidden away’ in a separate hotel during filming, and she had signed an NDA preventing her from revealing her return

Gavin and Stacey: The Finale drew in a whopping 12.5 million viewers to become the most watched show on Christmas Day.

Viewers had been waiting for five years to learn the fate of the BBC sitcom’s beloved characters and see if Smithy had accepted Nessa’s proposal.

The final episode was hailed ‘perfect’ by viewers, who were left in tears as the long-running show finally aired its last episode after 17 years.

The BBC won the battle of the channels when it came to ratings as 10 million also tuned in to watch the return of Wallace & Gromit: Vengeance Most Fowl.