Inside the door of Java's coffee shop on Abbeygate Street in Galway – just to the right of the menu – there's a collection of press clippings relating to the bistro's most famous former employee, a young American actor. Zachary Quinto spent a few months working there, in between his studies at NUI Galway, in the late 1990s.

Quinto – who is half-Irish on his mother's side – was already a seasoned thespian by the time he arrived in the City of Tribes, where he appeared in a production of The Bear with Tintreach Company. Indeed, he has been acting since boyhood, a pastime, he notes, that may be connected to the death of his father, who died of cancer when he was just seven.

“I don’t think it was solely responsible for me going into acting, but it definitely influenced it,” says Quinto. “On some level, I had a need for an environment in which I could explore all the emotions that came out of that trauma. I think acting, early on, provided me with that outlet.

“There were practicalities, too. Part of the reason I went to acting class was to do with my mom, who was a single mom who needed to know where her kid is after school. But once I was there, after a little while I realised: wait a minute, this is really my thing.”

The first time I interviewed an immaculately dressed Zachary Quinto (even his silk pocket handkerchief was beautifully folded), I found myself reaching for old-timey words such as “debonair” and “dashing”.

Today, the actor is on a mad 24-hour, whistle-stop press day for Star Trek Beyond, the third film of the rebooted franchise. Quinto has a touch of the cold and sports a tweedy sweater, and I still find myself reaching for the same old-timey words.

Of late, of course, Quinto has mostly been wearing large pointy latex ears for Mr Spock duties on Star Trek Beyond. The newest film in the 50-year-old franchise will premiere next week at San Diego Comic-Con on July 20th, at an open-air Imax screening backed by a live performance of Michael Giacchino's score performed by the San Diego Symphony Orchestra. Until then, Quinto can say no more.

“These aren’t always the most illuminating interviews,” he laughs. “Because we’re not allowed to give it all away. Or anything away. I can tell you the movie is going to be really exciting on a lot of levels.”

Star Trek Beyond’s predecessors – the 2009 and 2013 movies Star Trek and Star Trek Into Darkness – were directed and shaped by JJ Abrams, who was subsequently snapped up to usher Star Wars: The Force Awakens into a multiplex near you. Did the Trek cast have any abandonment issues?

“No,” laughs Quinto. “Okay, when I read that JJ was doing Star Wars, my first thought was ‘oh no’. So I guess that means he won’t be doing our movie? But, as JJ’s friend and as a fan and admirer of his work, then obviously I want JJ to do amazing things. Star Wars was such a big opportunity. I don’t think there was anybody else that could have done that job.

“So we were all happy for him. We do miss him. But he’ll be back.”

For the moment, the Trekiverse has been left in the capable hands of Justin Lin, of Fast & Furious fame, a director whose films have, to date, taken almost $2 billion at the box office.

“He’s such a confident visual director,” enthuses Quinto. “We all enjoyed working with him so much, and I hope that translates into the movie.”

Having first essayed the role in 2009, Quinto says that he almost “can slip easily and comfortably” into the Spock role. If only he didn’t have to suffer through 2½ hours in make-up, much of it spent plucking eyebrows. He does, it must be said, have quite an impressive pair.

“I know. I get it from both sides of the family. We’re all pretty heavily browed. But all that plucking and make-up and hair do so much to inform who that character is. Not that tweezers ever get any less painful.”

Sadly, Abrams wasn't the only departure Star Trek Beyond had to weather. Leonard Nimoy, who played Spock for more than four decades, died in February 2015 at the age of 83. Nimoy and Quinto shared the role in the two previous film and subsequently became firm friends.

“It’s one of the most iconic roles in popular culture,” says Quinto. “And I was always somehow reassured that I was sharing the mantle. That we were in it together. Now it’s all me. Which is a little weird. More than that, it’s the loss of my dear friend. But, you know, it’s interesting – and comforting – how much Leonard lives on in this world and through this role.”

Zachary John Quinto was born in Pittsburgh in 1977. It was, he says, "a really safe, great city for kids: families everywhere, tree-lined streets, very suburban".

He attended Central Catholic High School, where he won a Gene Kelly Award for musical theatre in 1995, and further honed his craft at Carnegie Mellon University's School of Drama.

Quinto soon relocated to LA and was playing Clov in a production of Endgame (he still treads the boards at regular intervals) when he landed a recurring role as computer whiz Adam on 24. But his big breakthrough came in 2006 with Sylar, the serial-killing villain of the sci-fi series Heroes. He worked on the show until it finished in 2010.

“I’ve been very lucky,” Quinto says. “And the luck hasn’t run out yet.”

The following year, at the age of 34 and moved by the suicide of gay teenager Jamey Rodemeyer, Quinto publicly came out as a gay.

“I made that decision to go public because I realised that we can’t move forward unless we’re authentic,” he says. “We have to stand up and acknowledge who we are.”

He has continuing concerns regarding the deep divisions in America’s bipolar, bipartisan politics, and how those can impact on LGBT causes.

"I feel like we are evolving past our limitations, and any evolution takes time. I don't think that people like Donald Trump represent the vast majority of Americans. God willing. But I do feel that there's a more general cultural tension in America where people are turning on one another. It's a scary time in that regard because it's about taking five steps forward and then taking one back.

"You get the Supreme Court ruling on marriage last year and then immediately you get the country clerk who refuses to issue marriage certificates to gay couples," he says. "There are people who want to cling to ancient vestiges with surprising vehemence. So we have to do all that we can to keep moving forward."

Having spent the guts of a year shooting Star Trek Beyond, Quinto is delighted to, once again, don his producer’s cap for a rather smaller indie drama called Aardvark. He previously produced the Oscar-nominated Wall Street thriller Margin Call.

“I love all the duties and responsibilities that come with the job,” he says. “I’m someone who lives and thrives on the sense of accomplishment that comes with challenges.”

Happily, the New York-based Aardvark has allowed him to return home to his boyfriend, the oil painter Miles McMillan, of an evening.

“I lived in LA for 13 years and I did love it there. It’s a beautiful, underrated city. Except, of course, when you’re sitting in traffic for two hours getting unnecessarily irate about the other drivers around you. But New York is somehow more reflective of who I am and who I always wanted to be.

“People often assume I’m native. And I don’t necessarily know what that means. But I like it.”

Star Trek Beyond opens on June 22nd