In the episode, which aired this afternoon, Billy and Chris Blanchard-Cooper from Thames Close got close to taking home the full amount - but a question about the Bible scuppered their hopes in one fell swoop.
Speaking afterwards, the couple said they loved the experience, but Chris added that moment they lost was surreal: "You just feel slightly shell-shocked, and then you think: oh, can I have another go?"
Presented by Davina McCall, the teatime show sees teams of two starting off with £100,000 and putting money on what they think could be correct answers to general knowledge questions of increasing difficulty.
The couple retained the full £100,000 after four questions out of seven - and despite dropping some money in the fifth round, they went into the penultimate round with an impressive £65,000.
Chris said: "We couldn't believe we had got so far with all that money there. We couldn't believe our luck; the categories seemed to be ones we had an interest in and were comfortable with... until that last one."
The Arun District Councillors avoided a politics category early on in the game, choosing auctions instead. But when theatre and actor categories came up, the musical-loving pair were in their element, despite Billy confessing that 'unless it is about Bette Midler, I don't stand a chance', which got a laugh out of Davina.
Billy said: "They didn't air it, but at one stage Davina said our win was going to be the biggest they had ever seen, because we got so far with so much of the money left."
Unfortunately, the question "What word appears most frequently in the King James Bible?" was their undoing. They put all their money on 'pray' and 'love', but 'eat' was the correct answer.
The couple both have previous experience on television game shows. Chris got to the final three on The Weakest Link 15 years ago, and Billy auditioned for the karaoke-themed Don't Forget the Lyrics as his drag alter-ego Miss Daniella Dream, only for him to turn down the producers when they asked him to be on it out of drag.
But after deciding they wanted to share the experience again as a couple, they applied for the show around September last year.
After a series of phone interviews, Chris and Billy were invited to an audition day in London where they failed on the first question.
Despite this, they were selected to be on the show; but the filming dates clashed with the Littlehampton Musical Comedy Society's pantomime, which Chris was directing.
However, the producers were so keen to have them on that the couple went up to the television studios in Manchester in late January to be among the final couples to be filmed.
Billy said something that struck him was how small things appeared compared to television: both the studio, and Davina herself.
Chris described her as 'lovely and down to earth': "As a group, we were taken on a tour of the studio before we met Davina, and the first thing you see in the corner of the set is Davina's high heel shoes, which apparently she kicks off the minute she finishes filming."
The pair only found out they were going to make the cut two weeks ago, when they were allowed to tell people they were on the show.
In the meantime, Billy said it had been hard to keep how they did under wraps, after being 'bombarded' with messages from friends and family.
While they weren't able to go on a holiday to Fuerteventura in the Canary Islands as they hoped, the pair said the experience was well worth it.
"On the bright side, we have our name badges as a memento at the very least," Billy said.