The Gavin and Stacey Christmas special has become the biggest scripted programme of the past 10 years as more than a quarter of the UK’s population has now watched it.

The sitcom, which returned after nearly 10 years for a one-off festive episode that reunited its creators and stars James Corden and Ruth Jones with Mathew Horne and Joanna Page and the rest of the cast, has been viewed by 17.1 million people, according to the latest consolidated figures.

The programme initially drew about 11.6 million viewers in the overnight ratings, and has now added another 5.5 million viewers over the past week. Consolidated ratings include people who recorded the programme on TV and watched up to seven days later.

It is now the biggest scripted show of the decade, the most popular Christmas Day programme of the decade and the ninth biggest transmission of the decade, the BBC said.

It has also had the most successful first week for any episode on the BBC’s catch-up platform iPlayer for those aged 16 to 34, with 1.4 million requests from people in that age group out of 4.4 million total.

The episode picked up 10 years after the previous instalment and revealed that Gavin and Stacey (Horne and Page) now have three children, while Smithy and Nessa (Corden and Jones) are successfully co-parenting their son, Neil.

The director of BBC content, Charlotte Moore, said: “Gavin and Stacey has been a phenomenal hit this Christmas, breaking records to become the biggest scripted show of the decade, and the biggest first week for any episode on BBC iPlayer for young audiences ever.

“Congratulations to James Corden, Ruth Jones and all the team.”

Gavin and Stacey joins one other non-sporting programme in the top 10 most-watched of the decade: The X Factor final in 2010, when 17.7 million viewers tuned in to watch Matt Cardle win.

The rest of the top 10 is made up of sporting events, with the Olympics 2012 closing ceremony in first place overall with 24.5 million viewers.

The London 2012 opening ceremony is in second place with 24.2 million viewers, while last year’s men’s football World Cup semi-final between England and Croatia is at third with an overall audience of 20.7 million viewers.