Douglas Booth: New romantic plays the heartthrob in new film adaptation of Romeo & Juliet

For a grown-up audience, it's easy to forget the, like, totally teenage nature of Romeo & Juliet. Shakespeare's star-crossed lovers are adolescents of course, (she just shy of 14), and not only does it offer perfectly giddy first love, but is spot-on with the juvenile self-absorption too; teenage passion, and petulance, turns out to be timeless. No doubt partly because of all this, Romeo & Juliet has long been a school curriculum staple, and there's nothing like set text status to make a production bankable.

That goes for films too, and anyone playing Romeo is pretty much guaranteed a captive, swooning audience of teenage girls. For my generation, Leonardo DiCaprio was Romeo. But he's surely about to tossed from the balcony, as a new young actor ascends. Douglas Booth (best known for playing Boy George in Worried About the Boy and Pip in Great Expectations) is Romeo in an adaptation by Downton Abbey's Julian Fellowes. It's directed by Italian Carlo Carlei who returns the action to romantic, sumptuous medieval Italy – but it's still a tragedy for our times. If the tattooed, drug-taking Montague boys in Baz Luhrman's flick represented punkish youths of the Nineties, this lot are more like the One Direction of Verona: very young, very pretty, very pouty.

Booth ticks every Romeo box: he speaks the verse rather prettily, he's convincingly soppy over Juliet, his legs look excellent clad in leather astride a horse, and he's paint-by-numbers handsome: almond eyes, pillowy lips, cheekbones so slanted and jaw so right-angled that teen fans could use 'em as a set square in maths.

He's also young: now 21, Booth was only 19 during filming. His Juliet, Hailee Steinfeld (Oscar-nominated for True Grit) was just 15; she makes for the most baby-faced heroine you've ever seen in a bedroom scene (fear not: the wedding night is tastefully skirted over, while still letting viewers perve at Booth's pecs). And such youthfulness is the film's greatest strength. Fellowes' textual liberties – which have upset some scholars – do sometimes feel unhelpful; the direction can verge on am-dram ham, and the score is horrendously over-bearing, off-the-scale schmaltzy – but the chemistry between the two leads is genuinely lovely. They may be smothered by bowers of flowers and treacly slow-mo, but they still manage to give a delicate, tender, truthful depiction of innocent first love.

"That was what I felt we could bring to this," agrees Booth. "Once I'd thrown all the baggage that comes with playing Romeo out the window, [I wanted] to take this as two young people at the very beginning of their lives, to take it afresh. And I think we did that."

Booth is keen to reach a new generation. "I hope – without losing most of Shakespeare's beautiful text – the way Julian has managed to edit it together, people can really follow it all, whatever age. It's not an exclusive thing for scholars. If it engages a younger audience with this story, then I'm more than happy to oblige. Sometimes I get girls come up to me saying 'I saw you in my English class' and you know, cool: I'm doing something good for education!"

Booth didn't find school easy himself – he struggled with dyslexia – and acting in this film helped him more fully embrace the Bard. He's recently seen Othello at the National, and is champing for a chance to do Shakespeare on stage; he even – with just a smidgen of youthful arrogance – lines himself up for the Dane. "Obviously every guy dreams of playing Hamlet, but before I do that I'm going to let the world catch up with me, [experience] a bit more of life and pain. I'm going to play it when I deserve to play it – if I ever get the chance to," he adds hastily.

For now, Booth's taking a breather, back in his home town of London. He's filmed three movies since wrapping Romeo & Juliet, including two big-budget but intriguing Hollywood films. Noah is Darren Aronofsky's Biblical epic-cum-family drama, starring Russell Crowe, Anthony Hopkins and Emma Watson; Booth plays Noah's son. Then there's Jupiter Ascending, the latest from sibling duo, Andy and Lana Wachowski. "They're just the most original people," enthuses Booth. "They've created something very exciting and special and bonkers. It's like a cross between The Matrix and Star Wars." The cast includes Mila Kunis, Channing Tatum, Eddie Redmayne – plus Booth's rumoured girlfriend, Vanessa Kirby.

And he's just finished filming Lone Scherfig's big screen version of Laura Wade's hit play, Posh. Dramatising a Bullingdon Club-style dinner that veers nastily out of control, the film delves further into the back stories of its over-privileged members. "We had a chance to portray them as real people," says Booth. "When you meet these sort of guys [in real life], they're always so charming. It's almost more discomfiting for the audience to be charmed by them, to like them a lot, and to see how far they'll go with them…"

It's still an angry piece though, and Booth – despite being terribly charming himself – is clearly pleased to do a project with topical, political bite (David Cameron, George Osborne and Boris Johnson were Bullingdon Club members). The film, naturally, has a cast of up-and-coming Brits, including Freddie Fox, Max Irons and Sam Claflin. "I made friends for life. We are very sociable as young British actors, very supportive – we truly love each other a lot," he gushes, setting luvvie klaxons howling.

But one of the press's favourite games with young British actors is to pounce on them for being posh – so this lot in a film called just that, well, the headlines write themselves… "That's bollocks," interjects Booth, a little less smooth, a little more prickly. His dad may be a banker, but Booth tells how his grandparents were immigrants (his mum's half Spanish, half Dutch) while his parents were bootstrap-pulling members of the working class, who put in years of graft to be able to give Booth and his sister "a decent upbringing".

"Certain people in our cast you could definitely call posher than others," he says, adding that others "are the complete opposite of what this film talks about. We're actors, and we're acting a play called Posh, and actually making commentary on it."

Having been in the industry since the age of 16, Booth already exhibits a wariness of tabloid spinning. He shoots down Daily Mail reports that Romeo & Juliet's release was delayed by reshooting, because he didn't have chemistry with Christian Cooke (Mercutio). "Total bollocks. No scenes got re-shot for this movie. They re-recorded the score. [The tabloids] like to lie because they are trying to earn their place in hell." He describes the British press – excepting "lovely" journos like yours truly, naturally – as "out to get you. You can't win; the best thing to do is just be yourself, and if someone doesn't like it, fuck 'em." But there's plenty to like about Booth, and his more-than-just-a-heartthrob choice of roles. Soon to graduate from Shakespearean teen dream to a political posh toff, he might just make the transition from Prince Charming to Prince of Denmark yet.

'Romeo & Juliet' is released on Friday