Actors Larry Lamb and Alison Steadman - who play Gavin's parents Mick and Pam Shipman in the BBC comedy - were pictured taking a break on sun loungers at the South Wales tourist spot.
The pair smiled and waved for the camera after they were spotted by children and teachers on a school trip to Barry Island, where Gavin and Stacey is set and filmed.
Sarah Williams was visiting the area with staff Sarah Briar, Charlotte and Samantha, plus children from Cylch Meithrin Rhymni, when they bumped into the celebrity duo on Monday (June 13).
The group was visiting to watch Welsh language show Dewin a Doti on the sea front - but got more than they bargained for when they also spotted Lamb and Steadman.
The appearance sparked speculation among excited Gavin and Stacey fans that a new episode could be in the pipeline.
Gavin and Stacey ran from 2007 to 2019, ending on a cliffhanger during the last Christmas special episode, which saw Nessa (Ruth Jones) propose to Smithy (James Corden).
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