Just over a year ago, Simon Godwin was all set to direct Romeo and Juliet at the National Theatre. The cast, including Josh O’Connor and Jessie Buckley as the star-crossed lovers, were just going into rehearsals when theatres went dark because of the Covid-19 pandemic. This production looked doomed to darkness, too.

But David Sabel, the producer who created NT Live, had an inspired idea, says Godwin. “There had been discussions between him and Rufus Norris [artistic director of the National] about transforming the space into a studio and doing something digital in a way that kept the essence of the stage.” It meant that the production could be seen, in its new form, by many more people than an auditorium allows. The film, with a starry cast including Tamsin Greig and Lucian Msamati, is broadcast on Sky Arts in the UK this weekend and on PBS for US audiences later in the month.

The film was shot late last year, utilising everything from the repurposed Lyttelton stage to storerooms and corridors without once venturing outside. “You realise how many scenes are set in piazzas and streets with a lot of sunshine and heat, so there was the question of how to solve the conundrum of conjuring the outside without ever going out,” says Godwin.

It was a sharp learning curve for Godwin, who directed Antony and Cleopatra, starring Ralph Fiennes and Sophie Okonedo, at the National in 2018 and became artistic director of the Shakespeare Theatre Company in Washington DC the following year. He had never directed for the screen before. “The rehearsals were familiar ground, but the rest of it was like film school for me. So much of my directing is about saying, ‘Can you do it a bit louder?’, especially at the National. Jess and Josh were much more experienced in film than I was so they knew to do monologues with much more intimacy.”

O’Connor says that he also felt as if he was grappling with a new medium: “It was a discovery for all of us because it’s not like film and it’s not like theatre, so we were all relearning.”

There are some bedroom scenes in the film, which contain a surprising degree of physical intimacy. How did the film get around social distancing for those moments? “Most of the time we wore masks. Twice a week we were tested and immediately after we got the results back, Jessie and I had a three-hour window to get intimate,” says O’Connor.

The hybridity of the project opened up new creative possibilities, Godwin says, and he was able to use techniques such as flashbacks/forwards, which added to the play’s theme of foreshadowed fates. “I wanted to celebrate what it could give us that the theatre cannot. Its hybridity is its greatest strength.” Ingeniously, it is both the story of Shakespeare’s lovers and of the play’s transformation from stage to screen. “The film itself is trying to capture the journey of performance and what it feels like.” Buckley agrees: “You’d be silly to not acknowledge what this was in its own unique way. It was beautiful to see the innards of the theatre behind you. That was part of the tapestry of it.”

Verona here is in modern-day Italy and actors are in contemporary dress. Fisayo Akinade plays Mercutio as an openly gay character, which he thinks gives the character a certain defiance. “Initially we were thinking of setting it in the late 80s or early 90s and in a very religious [Catholic] society. So Mercutio’s choice in that context would have been a really radical act, and that sort of remained even though we made it more contemporary.”

Akinade has performed at the National, in Barber Shop Chronicles and The Antipodes, but felt he acclimatised to the cameras fairly quickly. “It was interesting marrying theatricality with the technical requirements of film. You couldn’t run across the room but there was real excitement in being able to convey a lot that you wouldn’t be able to convey traditionally on stage – there’s a lot more you can do with a look or a head tilt. There was a precision in it and I loved that challenge.”

He is, however, desperately missing live shows and hopes that hybrid productions with starry casts do not sideline live theatre in the future. “The thing about making films is that you need star names to get them made. It’s not the same for the stage unless it’s the West End. If more of these films get made, it would be good to elevate newer talent.”

• Romeo and Juliet is on Sky Arts in the UK on 4 April and on PBS in the US on 23 April.