In a hotel in Soho, halfway through my allotted interview time with actor and singer Johnny Flynn, the director of his latest film, Autumn de Wilde – a decadent and stylish adaptation of Jane Austen’s perennially-loved Emma – sneaks into the room and blindsides the actor with the gift of a shrunken top hat, no less.

Such antics illustrate the close nature of the glittering ensemble cast, including Anya Taylor-Joy (as the titular character), Bill Nighy, Mia Goth, Miranda Hart, Josh O’Connor and Callum Turner – which sees Flynn star as George Knightley, the dashing neighbour of Emma Woodhouse, who becomes unwittingly embroiled in her matchmaking antics.

Expect bickering, dancing, nudity, grand proclamations of love, and a spot of singing by a pianoforte – we caught up with the actor and talked about the magic of the film, and how he’s a romantic at heart…

Congratulations on the film. How did you first get involved with Emma?
I was doing a play at the time when I received an email from my agent saying they were making another version of Emma. And so I was living in such a different world to Austen’s Regency England at the time. I was in 70s California but still had the mutton chops – so that was helpful.

When I went to meet Autumn, I knew [Emma] was a book I loved studying at school. And as soon as I met Autumn I realised it was going to be very special and different. Even from the level of care in her pitching: she had this box and everything was so beautiful. Inside it she had references to the set and costumes and characters, not just a piece of paper saying “this version of Emma will be…” She’s so kind of magical. Then I did this sort of chemistry read thing with Anya, and that felt really special as well. We did one of the arguments, and there was this energy that you rarely feel when you first meet and read with someone.

Bill, Miranda, Josh. There are a lot of hilarious actors in the cast – were there any points you just couldn’t keep a straight face?
Many bits. Any of the big group scenes. The Christmas banquet where Josh says “it’s starting to snow”, and we invented this thing where Mr Woodhouse [Bill Nighy] is totally freaked out by the snow, and he adlibbed “it was snowing the night your mother died.” Autumn directed it like a screwball comedy, and she kept on pitching references from 30s Hollywood comedies and Marx Brothers films. So we had all that kind of whip-smart stuff and that was all very funny. There was a lot of laughter. It was such a great gorgeous bunch of people.

The nature of period dramas in themselves, especially the dynamics between you and Emma evokes such a romantic swoon-factor – do you consider yourself a romantic?
I guess so. I like romance. I think there’s something quite nourishing in telling those stories, and people’s hearts being healed and connecting those hearts and it all coming together in a joyous way. It’s not part of my design in my career [to choose romantic roles], it’s just that these great opportunities come along. I do these fantastic character roles and played some interesting people, but I also tend to get cast as sort of everyman characters, or someone whom the audience can see themselves, or project themselves on to. In Knightley’s case they project themselves onto him but also they see Emma through him.

You’ve starred in such a plethora of genres, from unsettling horrors to period dramas – what’s the most calming thing about working on a horror and what’s the most terrifying thing about working on a period drama?
I think it’s really scary to play people who are essentially really good. Because there’s a sense of duty and responsibility to that, to honour that. With a character that has all those corners and twists and turns in sort of horror/thriller environments, you have all these moments to bounce off, but somebody that’s just a good constant person, you’ve got nothing to hide. So you have to keep opening yourself and being really raw, and it’s scary to be vulnerable. Because if you don’t open yourself the audience will feel that. They’ll feel excluded from your heart and you won’t be doing your job.

Working on a horror, I’d say it’s actually quite calming, especially like in the case of Beast when you know you’re the murderer, and you won’t be shocked by any revelations. Like I’m playing Ian Fleming at the moment in this kind of World War II thriller and I’ve got a wig, military coat and a walk, and a cigarette – and these are fun props to have because you can just do those things. And that already takes you far away from yourself, but if you’re playing one of these open-hearted characters it’s more inner-reaching.

I heard from Anya that you have a group Emma WhatsApp chat – what was the last thing you posted on it?
It’s quite active and quite intimidating, and I’m just generally a little bit shy when it comes to some social situations. And although I felt deeply in love with everyone, some people are like really on it with social media, and I’m still a bit suspicious. But I was aware that I hadn’t posted anything in a really long time, so I wanted to get this outburst of love for everybody. So I wrote this epic long poem pretending using everybody’s names in a kind of surreal, like silly tongue-in-cheek way, like “at the end of de Wilde Nighy, somebody has to pick up de Bill.”

The scene in which you sing – was that already part of the script or was it a suggestion of yours? Do you relish it when the two worlds of acting and music collide, or do you like keeping them separate?
I used to try and keep those two things separate, so I could try and maintain my integrity with both of those things. And be taken seriously as both an actor and a musician. But now I’m feeling secure enough now that I can cross over, and I really like it when it happens. In this instance I was able to write a love song to Emma from Knightley’s perspective. It’s his kind of celebration of her but a very tongue-in-cheek teasing one that feels true to the way a good marriage would be – you know the way people communicate when they’re in a good marriage. With my wife we definitely tease each other a lot, and so it was fun to do the song. It was my icing on the cake in my portrayal of [Knightley].

Read the interview with Emma’s Mia Goth. Emma will be released in UK cinemas on 14 February.