The first time I met Cillian Murphy was at the Traverse Theatre, Edinburgh, in 1997. The actor, then 21, was making his stage debut in Disco Pigs, a two-hander about teenagers from Cork, Ireland, a frenetic story about friendship and first love.

Even then, in tight-fitting silver trousers that looked like tin foil, fearless, feral, Murphy had a magnetism that ricocheted around the room. That ethereal face, that deep, laconic Irish accent, those ice-blue eyes held everybody in his thrall. He would wind down after each performance with several pints (and an odd obsession with Chumbawamba) with the company, a wild gang who were all great friends. Had you asked me then if he might one day win an Oscar, I would have nodded: absolutely, yes.

Last month Murphy picked up his first Academy Award for best actor for Oppenheimer, crowning a 28-year career. Thanks to Danny Boyle’s 28 Days Later, six films, including Batman, with the filmmaker Christopher Nolan, and Peaky Blinders, Murphy is established as one of the best-known actors of the modern age. He has also continued to pursue new roles in theatre, working regularly with the same creative team. Enda Walsh, who wrote Disco Pigs, is now my husband, and he and Murphy still collaborate every few years. As such, I’ve long had a ringside seat to his successes and know his wife Yvonne McGuinness, an artist, and their children Malachy (18) and Aran (16), who now live in Dublin. A testament to his universally attractive features: as a toddler, my daughter would call him “Kiki” and try to stroke his face.

Our first meeting for this profile took place on the HTSI shoot at Wapping Power Station, Shadwell, a relic of Victorian engineering that is as far removed from glamorous as it is possible to be. Murphy was holed up in a “luxury” trailer, with the heating set to furnace, drinking mugs of herbal tea. The shoot had gone well and he was in a bonny mood: “I actually like taking pictures. I love trying to find the mood with the photographer and the stylist. When it’s a collaborative thing.” Murphy is now 47, with greying hair and a slight ruggedness about the eyes. He’s still absurdly handsome, especially when dressed in his off-duty sweater, jeans and workman boots.

In early February, Murphy was at the midpoint of the awards campaign. He was jetting back and forth from Hollywood for countless dinners and meet-and-greets, and dozens of ceremonies that would make the presidential trail seem tame. His odds for winning had become a near done deal, his fame had reached another tier. In Ireland, he had reached the zenith of recognition: his former primary school had swagged the school gates in a banner wishing him good luck at the Academy Awards.

For a man who has always steadfastly avoided press attention, the new scrutiny found him somewhat overwhelmed. “He is the world’s best actor and the world’s worst celebrity,” said his co-star Emily Blunt recently when asked about his attitude to fame. Murphy acts like a spooked cat around most journalists; he has no social media platform. He specialises in an expression poised between disappointed and bemused. “Everyone knows that I’m the most fucking memed awkward person on the internet,” he cringes when I mention a TikTok that sees him ambling into the Golden Globes alongside the caption: “When you made plans while you were feeling extroverted and now you have to attend.” “Can’t I just be normal?” he says. “It is nuts, you know?”

In spite of appearances, however, Murphy has been having fun: he’s even allowed himself to have been photographed in public with Yvonne, a very rare occurrence in their 20-year marriage. “I am enjoying it, because I’m choosing to enjoy it, and I think there’s a distinction,” he says. “And this is celebrating the work that we did, and you have to go into it with an open heart.”

He reminds me of another Cork-born legend, the Irish midfielder-turned-football pundit Roy Keane. Both share the same congenital disposition to seem utterly nonplussed. “[Roy Keane] is actually one of my favourite people,” says Murphy. “I met him once in an airport, and we had a very intense chat for about an hour and a half.” Did he see a kindred spirit? “I did,” says Murphy. “He’s got that thing, that Cork sense… straight to the heart of the issue. He’s a legend. Everything he stands for, I love.”