Ghosts, the beloved BBC One sitcom about a found family of unexpectant stately homeowners, and their needy gaggle of ghostly housemates, returned for its fifth and final series last Friday. But a few days before, The Mirror forced the cast into prematurely confirming on X that "there might be one last present under the Christmas tree this year."

"[The leak] was kind of inevitable," says Laurence Rickard, one sixth of the Horrible Histories troupe who both write and star in the series. During production, press had visited the set (the grand and Grade 1-listed West Horsley Place in Surrey) on the same day that the Christmas tree arrived for the special. "So there were a couple of clues if you were looking for them!" he laughs.

To be fair, most would have seen another special coming. The BBC have made a visit to Button House a staple of its festive line-up, and for good reason: if Christmas is the holiday that brings families together, then Ghosts has become the Christmas of comedies.

Ever since it first aired in 2019, Rickard and his troupe have pulled off that increasingly rare feat of making both parents and their children laugh. As with the best of their Horrible Histories sketches, it is silly and broad but genuinely hilarious, and the impressively high gag rate doesn't let up in the new series.

It's business as usual in the House (which is to say there's not much business going on). After their B&B burned down at the end of the last series, Mike is anxious to fix their finances, but Alison, the inheritor and put-upon spiritual medium of the home, is too busy teaming up with Rickard's own headless Tudor, Humphrey, to prank each of the ghosts in turn.

Here's Thomas Thorne (Mathew Baynton), the hopeless romantic and failed Regency-era poet who's been pining for Alison for all of five series, laughing manically after she fools him into thinking he's finally won her heart. And here's the starchy Lady Button (Martha Howe-Douglas), sent into an archaic tirade by Alison's fake tattoos: “my own kith and kin, branded like some lowly navvy, painted like a tawdry jezebel!”

Given that the ensemble is in such a well-worn groove, why stop the dance now? "It was very much a head over heart decision," says Rickard. "It's such fun and we could have kept doing it forever."

Besides the old showbiz adage of "always leave them wanting more," divulging the last few backstories of the ghosts meant that, were they to carry on, they would have to change the format. Also, "ghosts can't age. And after five years, there are a few more grey hairs and eye bags that we were working around..."

The characters are now so lived-in that some of the cast have shed their prosthetics. To play Lady Button and all her "weird goosenecked expressions," Howe-Douglas used to have a prosthetic neck fitted to aid what's always looked like headache-inducing facial contortion. But apparently, as fans have emboldened her to pull bigger and bulgier faces, she's found even greater range in her performance without it.

Patience is clearly a virtue in their writers' room. Despite painting "the broad strokes" of all those backstories back in series one, the troupe has spent the next four carefully parcelling them out. Crucially, though, such a plot device has never felt like a cynical ploy to keep viewers on a leash, but rather a natural, step-by-step growth on the part of the characters.

Perhaps the best example of this is The Captain, Ben Willbond's ghost of an uptight WWII army officer whose backstory of tragic romance is tied up so tenderly in the last series. (Yet another virtue of the comedy is that it has never shied away from the tragedy of its premise: the ghosts have all had their lives cut cruelly short).

Flashbacks had continually hinted that 'Cap' was in love with his Second-in-Command during his Button House posting. But, says Rickard, "we kept it deliberately nebulous whether he even knew. As the series have gone on, we more and more felt like he did, but never felt that he was able to share it, even now, when his life is over, when society has changed and when that sense of shame has gone away. It's such a big step for him that it needed to feel like it took time, and not trite or dismissive."

There was, however, one storyline that not even the writers saw coming. Rickard cites their 2023 Comic Relief sketch with Kylie Minogue as a "pinch yourself moment." Minogue had previously reached out to profess her love for the show after watching 'Happy Death Day', which sees Thomas overhear I Should Be So Lucky and accidentally pass the lyrics off as his own poem for Alison. So when Comic Relief came calling and asked the team for their perfect cameo, only one came to mind.

"She was just so up for it," says Rickard, "and completely got the tone of it." But even Simon Farnaby (Farnaby plays the moral-less and trouser-less MP Julian), who he says is normally the picture of calm, melted in the presence of the Princess of Pop. "He was immediately like, [his voice deepens as he mock-grovels] 'do you think we can come to a concert?'"

The troupe's not-so-secret ingredient is the sheer sense of fun they bring to everything they do. Just check out the blooper reels, which give you the impression of a set where the prime motive is simply to corpse one another. Rickard says it's often mistaken for improvisation, when, in reality, the series is 95-96% as-scripted.

He blames such anarchy for leading to scripts riddled with innuendos. He's adamant that the ghosts' term "sucked off" is "a perfectly acceptable phrase for moving on to another astral plane!" But he admits to there being "an unofficial Fanny count" in each episode (Lady Button's first name is Fanny) to make sure they don't step over a line.

"It's a bit like pulling down your beards, letting the actor shine through and going, 'look, it's us, we're being silly.'" He hopes it never feels self-indulgent; at the same time, he says, "I'd hate to lose that — everyone behaving too much would be a bad thing."

Almost all of the series was shot in and around the house itself, so as well as complimenting their "brilliant art department" for redressing the rooms to resemble all of doctors' surgeries, solicitors' offices, cafes and nightclubs, Rickard describes the insular production as "a bit like going on a retreat with your mates for two months during those dark, first couple of months of the year."

Having to drive into make-up at 5.30am, he had the earliest starts ("the only downside to playing a caveman"), but he speaks of Button House as his "second home" and admits that what he'll miss most is "the company" (including their post-shoot Wagamamas).

It's when you hear them talk about each other like this, and of all the fun they had filming, that you can understand the outpouring of emotion that came during the final days. Rickard says that most of them were convinced they had pre-grieved, until, on the last day, "everyone went at some point. The DOP, the Unit Stills... It's like sniping, because you kind of take each other out."

It didn't help that due to a fatal quirk in the shooting schedule, the very final scenes they shot were also the very final scenes of the Christmas special. "So yeah, the ending was a bit of a double whammy emotionally."

Having brought the funny and a familial warmth to all of five series, come Christmas we'll all be in mourning as Ghosts gets "sucked off" our screens.