Gavin & Stacey Christmas Special, BBC One (4 stars)

Gavin & Stacey Christmas Special, BBC One

Expectations are exceeded with this festive return of Ruth Jones and James Corden's beloved sitcom

With its focus on disparate families rubbing along and an easy sentimentality that's seldom mawkish, Gavin & Stacey is perfectly geared up for a Christmas special. And indeed, to a one-off revival, with the festive gathering a logical reason for reuniting the Shipmans, the Wests, and their extended and expanding broods, the twenty-something lovers of the early series now middle-aged parents. Nevertheless, writers James Corden and Ruth Jones have surpassed expectations with this hour-long treat, which not only justifies its return but makes a strong case for bringing back the sitcom for further episodes.

Against the backdrop of chaotic preparations for Christmas dinner in Barry, with host Uncle Bryn (Rob Brydon) at a constant fever pitch of anxiety, Stacey (Joanna Page) worries that raising kids has led to the spark depart her marriage to Gavin (Mathew Horne). Virtually every romantic sitcom of any vintage will explore this theme at some point, but Gavin & Stacey mines its own mythology and nostalgia legacy more satisfyingly and with more credibility than most. The karaoke duet of Bryn and Nessa (Jones) has become part of family tradition within the show, with an intimidating Nessa enjoyably snarling through Shane MacGowan's part in a rendition of 'Fairytale of New York'. Meanwhile, an unthinking moment from Gwen (Melanie Walters) threatens to finally reveal the dark secret of that fishing trip so regretted by Bryn and Jason (Robert Wilfort).

What truly makes the episode though, is the deft way in which the show introduces the girlfriend of Smithy (Corden), the well-meaning but bum-note Sonia (Laura Aikman), into the established chorus of eccentrics, and the impact it has upon Nessa and Smithy's efforts to co-parent their adolescent son, Neil the Baby (Oscar Hartland). Nuanced, funny and relatable, the special's conclusion will doubtless bring about widespread calls for the show to return once more.

Gavin & Stacey Christmas Special airs on BBC One, Wednesday 25 December, 8.30pm.