The third and final series of Derry Girls will end with a surprise double-length seventh episode set one year in the future, as the band of friends turn 18.
The show - Channel 4 ’s biggest comedy since Father Ted launched in 1995 - is in the middle of its six-part run, which creator Lisa McGee has declared will be the last ever.
But after it ends next month, fans will be treated to an extra hour-long episode which takes the gang to the polling station for the Good Friday Agreement referendum of 1998.
And - following on from Liam Neeson’s appearance in the opener as a disgruntled policeman - other big name stars have been lined up for the big swansong.
Lisa told the Mirror: “Like all the very best 90s bands, I couldn’t resist ending our farewell tour with an encore for our loyal fans.
"I'm delighted to say we'll be returning for one extended special - airing in the same week as our final episode.
"The special deals with the historic and momentous Good Friday Agreement vote, which coincides with the gang’s coming of age, they enter adulthood just as Northern Ireland embarks on a new future.
“I’m so proud of this show and of our incredible cast and crew and everything we’ve achieved over the past five years. What a journey it’s been.
"I'm so grateful Channel 4 gave me the space to end the stories of these characters that mean so much to me with this special. I really hope the fans love it as much as I do.”
Lisa, who grew up in the town herself and says she is “always a Derry Girl”, added: “Derry people aren’t great at saying goodbye so I will instead use one of our native expressions: ‘That’s us away now’.”
In the episode, the girls - and James - are preparing for their final year of school. It’s the week of the referendum on the Good Friday Agreement but they are furious over the timing because it threatens to overshadow the highlight of the year - Erin and Orla’s joint 18th Birthday party.
Get all the biggest showbiz news straight to your inbox. Sign up for the free Mirror Showbiz newsletter.
The series, which launched in 2018 to widespread acclaim, stars Saoirse-Monica Jackso, Louise Harland, Nicola Coughlan, Jamie-Lee O’Donnel and Dylan Llewellyn as five teenagers living in mid-1990s Derry at the tail-end of the Troubles.
The gang attend Our Lady Immaculate College, a fictional girls' Catholic secondary school, run by the ever-cynical Sister Michael (Siobhan McSweeney).
At the start of series three, Neeson made a surprise appearance as a policeman trying to get to the bottom of the school robbery in which the girls got caught up. The hour-long special will have more guest stars, with one source promising: “It’s a corker.”
The extra instalment looks likely to air on Friday 20th May, a few days after series three finishes its six-part run on Tuesday 17th May.
The TV schedules will be confirmed next week.
Do you have a story to sell? Get in touch with us at webcelebs@mirror.co.uk or call us direct at 0207 29 33033.
