Gavin and Stacey viewers spot surprise cameo during Christmas finale that you might have missed

Throughout the 17 years that Gavin and Stacey has been on air (give or take), producers and writers have continued to invite hoards of big-name celebrities to make one-off appearances.

And naturally, this tradition extended into last night's grande finale, with one acting veteran and award-winning star rocking up for a supporting role during Smithy's long-awaited wedding.

Viewers were forced to wait five years to find out whether Smithy (James Corden) said 'yes' or 'no' when Nessa (Ruth Jones) popped the all-important question on Christmas Day 2019.

And when last night's ep kicked off with the gang planning some nuptials, fans thought they finally had their long-awaited answer...

Only for it to be revealed that Gavin (Mathew Horne) had interrupted their big moment, that Smithy had never given Nessa a real answer, and that he'd gotten engaged to girlfriend Sonia (Laura Aikman) in the meantime.

Naturally, the group had their reservations about the big day, believing Nessa to be a better match for Smithy than his hissy-fit future Mrs - something they only decided to voice when the wedding finally rolled around.

Ruth Jones as Nessa (BBC)

Prior to this point, however, a pretty A-list British actor rocked onto the set, having been hired to officiate Smithy and Sonia's wedding.

The vicar was none other than Anna Maxwell Martin, the much-loved Line Of Duty star also famed for her roles in BBC comedy Motherland, and the serial drama Bleak House.

After being invited by Maxwell Martin's vicar whether or not they have any objections to Smithy and Sonia's wedding, Gavin expressed his doubts, after which all other members of the squad stood up to demonstrate their concerns.

Maxwell Martin made a cameo last night (BBC)

The 47-year-old actor appeared at last week's premiere, leading fans to assume that she may have a possible cameo role in the production - speculation that has finally been confirmed.

And viewers were absolutely delighted by Maxwell Martin's appearance, with one penning on X: "Also love that Anna Maxwell Martin was in Gavin and Stacey. Now come back in Motherland. Please and thank you."

Another gushed: "Gavin & Stacey: laugh out loud bits include 'are you really wearing those shoes?', maybe because I was in a wedding this year. And realising the bemused celebrant was the wonderful Anna Maxwell-Martin."

"I don’t even like Gavin and Stacey but Sheridan Smith AND Anna Maxwell Martin….what a surprise," a third went on.

As we say, Maxwell Martin isn't the first celebrity to have made a cameo appearance in the fan-favourite sitcom.

For Nessa's previous nuptials to 'Dave Coaches' in the third series, John Prescott rocked up, having previously been referenced by her as an ex-lover.

At the same wedding, Gwen (Melanie Walters) and Stacey's (Joanna Page) neighbour Doris (RIP, queen) brought Hear'Say's Noel Sullivan as her date, having joked about striking up a romance with the singer.

Smithy eventually saw reason and ditched Sonia at the altar (BBC)

If you haven't yet sank your teeth into last night's episode, but can't wait to watch it on BBC iPlayer, don't worry - Smithy did eventually see reason in the objections against his marriage to Sonia.

And after a teary revelation, he fled the church and went to find Nessa, professing his love to her and the pair tying the knot.

Awww - it's the happy ending we always hoped for...