The band - Neil Tennant and Chris Lowe - arrived as last-minute headliners for the show's music festival Loxfest after the original act dropped out.
Listeners heard festival organiser Roy Tucker reveal the news backstage as village landlady Jolene Archer belted out a version of Dolly Parton's song of her name.
The duo, whose hits include It's A Sin, Go West and Heart, said: "It's a thrill for us to enter the world of The Archers, the UK's most famous radio drama."
They are joined on the show by Radio 6 Music DJ Steve Lamacq who is heard organising the festivities of the fictional festival.
He said: "Loxfest is the Archers storyline we've been waiting for. So when we first heard the rumours about the festival at the start of the year we offered up our services, helping to suggest bands that might fit the bill.
"I'd have probably have gone down and helped them put up the security fencing if they'd asked."
Previous guest stars include the Duchess of Cornwall and Princess Margaret.