Gavin and Stacey cast reveal behind-the-scenes details after final episode

Now that's commitment to the role!

Laura Aikman, who plays Sonia, was one of the most disliked characters in the show's history when she first appeared in the previous Christmas Special five years ago.

She single-handedly ruined the Shipman/West family Christmas in Barry when she arrived just after everyone had consumed their turkey, and immediately began bossing Smithy around.

While many thought she wouldn't be seen this time around, she cropped up about 20 minutes in to last night's finale, much to the surprise of most of the country and, as it turns out, the actress' own family.

How she managed to keep that news from her family for the last few months is beyond anyone's comprehension!

The actress also revealed during a Q&A with fans that she stayed in a different hotel to the rest of the cast and crew during filming in order to protect the storyline.

Not only would that have helped preserve the secret of her appearance, but it must have also served the tension and dislike between her and the Shipman/West crew on screen.

Fans took to social media after the big reveal to vent their frustration that Smithy was not only still in a relationship with the unlikeable Sonia, but that they were engaged to be wed.

One X user wrote: "Amid everything that was perfect about that Gavin and Stacey finale, the sheer monstrousness of Sonia deserves a more than honourable mention."

Seventeen years after the much-loved comedy’s first episode aired, the end of an era came in the form of a one hour and thirty minute special at 9pm on Christmas Day.

While last night marked the end of the story, a one-off behind-the-scenes documentary called A Fond Farewell will air on New Years Day on BBC One.