Film junkets are not usually a joyful experience. Locked in the depths of glossy hotels, actors on the promo trail do hours of interview after interview, filming and poster-signings, with hotel room service in between. Admittedly, life could be a whole lot worse but the point still stands: It’s rarely fun for anyone involved.

When HuffPost UK interviewed ‘Mamma Mia! Here We Go Again’ star Jessica Keenan Wynn, things were decidedly different. For a start, the standard set-up of two chairs and a backboard with a logo is gone and in its place stands a full recreation of a taverna, complete with window boxes, plants, blue tiles and wicker chairs.

“Welcome to Greece!” Jessica beams, clearly excited to continue talking about ‘Mamma Mia 2’.

Her peppiness is in keeping with the film itself as watching ‘Mamma Mia 2’ is one of the most joyous cinema experiences you’ll ever have. It’s impossible not to tap your feet and even the most cynical cinema-goer will eventually surrender to the power of ABBA, Cher and gorgeous shots of the Croatian island, Vis, which doubles up as the fictional Greek island Kalokairi.

“We need a feel-good summer movie that has these themes,” Jessica declares. “We don’t gloss over grief or loss, I think the movie handles it really well and then shows that love prevails.

“I think that it is the perfect time for that message to be relayed to the world,” she adds purposefully. “And I think people are going to it eat it up and want more.”

The 32-year-old is one of the ‘Mamma Mia 2’ newcomers, playing a younger version of Christine Baranski’s Tanya, Donna’s straight-talking, glamorous friend with all the best lines. It’s her first big screen appearance and Jessica describes getting the part as “sort of a ‘come to Jesus’ moment”. It’s quite clear that she hasn’t stopped thinking about huge this is.

“I’ve peaked,” she quips with a jokey shrug. “Thank you so much, I’ll be working on a kale farm for the rest of my life in Boulder, Colorado.”

While it’s her first feature film, Jessica has come armed with years of Broadway experience, including over three years in the Carole King musical ‘Beautiful’, which levelled the playing field when it came to acting alongside seasoned film stars in this long-awaited sequel.

“Going onto that set on the first day of rehearsal, I realised that everything I love and I’ve worked so hard for, I can literally just take that and walk it onto set and feel confident and like I belong,” she says. “I was doing a musical, where a lot of the other actors had never done a musical and never sung, so they were terrified and I had this sense of confidence.

“I hadn’t done a big movie but this was my element. This is what I had worked so hard for.

“It allowed me to psychologically grasp what it was we were doing and to enjoy it and feel like i belonged and that I was meant to be there.”

A big fan of Christine Baranski, Jessica knew how she was going to create the younger Tanya immediately. Taking cues from the star’s other projects, she “looked at ‘Cybill’ [and] the way she would gesture and grab a glass, and then in ‘The Birdcage’ it was how relatable and charming she was”, before “tying a little bit of Jessica into it”.

“The flirting was really easy,” she laughs. “Being a man-eater was quite easy. it’s interesting because I feel like Tanya informed so much of me.

“She’s a gorgeous statue and so putting her on for five months, I was like, ’I like the way this feels, maybe I’m going to attract some nice male attention.”

“It took a while but it might have worked,” she adds coyly, with another laugh (Jessica’s laughter features frequently, by the way). “But we will see… It was really fun to have the character inform me as a person.”

Jessica’s first scene comes when the young Dynamos launch into a tone-setting rendition of ‘When I Kissed A Teacher’ at the end of Donna’s graduation ceremony. It was filmed at Shepperton Studios, Surrey, and it was during the final rehearsals for this number that Jessica came face-to-face with Christine for the first time.

“Ol Parker [director] dragged in Christine, who was possibly there for a fitting, and he was like, Christine’s going to watch you guys practice!’,” she says. “He said, ‘Come on, do the number for her’, and I had a mild internal meltdown… and then we did it and she was beaming. Of course my eye just kept going to her.

“She gave us a standing ovation and was so enthusiastic.”

At this point, Jessica sits up in her chair and gathers herself for an impeccable impression of “one of the biggest influencers of my life”. “She said, ‘Girls you go and get it. Just don’t break an ankle in those boots’.

“I had to leave the room for a minute and take it all in.”

The rest of the movie was filmed in Croatia and Jessica describes the whole experience as “adult summer camp”. “You’d go to breakfast and then there’d be Colin [Firth] and Pierce [Brosnan]. Judy Kramer [‘Mamma Mia’ writer] would walk in. And oh, there’s Lily [James] and her boyfriend [Matt Smith].

“It was like we were all on holiday together and we had to kind of slap ourselves and, ‘Oh wait, we’re working’. But then you’d get picked up to go to work on a boat and take a boat through the sea to another part of the island and you’re like, ‘What is happening?’”

When she wasn’t busy filming (in true summer camp style, they didn’t shoot at weekends) Jessica explored the island, but there was one scene she was never going to miss the chance to see up close: Cher’s big number.

“I snuck onto set that day because I was there for a spray tan,” she says. “That was probably one of my fondest memories of the film because I felt like I was getting an intimate concert with this strong, gorgeous woman who I think represents so many beautiful qualities.

“She’s a goddess, essentially. I didn’t need to talk to her or be introduced, I just wanted to be in her presence and watch her perform because truly there is no-one like her.”

Jessica later names Cher’s version of ‘Fernando’ as her favourite ABBA song, explaining: “It is so brilliant and intimate that it just kind of takes on a completely different sound to the original recording.”

It quickly becomes clear that filming ’Mamma Mia 2′ was an absolute dream and there’s even a cast WhatsApp group where they all stay in touch. But there must have been some downsides, surely? Any tantrums on set? Incredibly long days of filming? Sunstroke, even?

“I did get food poisoning once…” Jessica says, after racking her brain for some bad moments. “I feel like I could say… we shot a scene in Oxford in November and it was freezing but we were giggling and laughing so much.

“So yeah, temperature is the worst thing about the experience. There’s nothing.”

With time almost up, the obvious question of what’s next beckons and after three and a half years on stage (with ‘Mamma Mia’ sandwiched in between), it’s one Jessica welcomes. 

“I can’t wait to make dinner at 8pm on a Thursday or have a Bloody Mary,” she says, busting out that laugh yet again. “What’s brunch? I don’t know what brunch is. I’m usually doing a matinee at 2pm on a Sunday so maybe i’ll have brunch. Go out on a date… Watch out boys, I’m coming loose!

“I feel like I’m so known for comedy, I’d love to do the complete opposite,” she adds, getting slightly more serious.“I need something to balance ‘Mamma Mia 2’, the happiest god damn movie in the world.”

Perhaps Jessica should sign up to a seriously bleak film? “I’ll tell my agent, ‘I would love the most depressing movie… If they’re doing ‘Schindler’s List 2’, let me know!’”

‘Mamma Mia: Here We Go Again’ is in cinemas now. Watch a clip from the film below…