The topic? The weather, of course, and he's complaining. Given that it's pouring with rain outside, this might sound reasonable. But the Elgin-born actor – and one of the stars voicing Brave – is at home in Los Angeles, where the sun shines 329 days a year. I, on the other hand, am in Glasgow.
"It's a bit grey just now," he tells me. Good, I say. He laughs and admits he tends to see Scotland through rose-tinted glasses. "As you say, it's lashing down there, but all my memories of living in Partick, Edinburgh and Elgin are perfect – but we know that isn't the reality. I overly romanticise Scotland sometimes."
For all that McKidd, 38, has become a star stateside – with a flawless American accent as Dr Owen Hunt in the US drama Grey's Anatomy – he remains as Scottish as they come. He recently recorded a charity album of Scottish folk music with a group of friends from Elgin, entitled the Speyside Sessions, which went straight to No.1 in the iTunes world music charts. He's also the new face of The Macallan whisky (McKidd has fond memories of working at the distillery in his late teens) and after the LA premiere of Brave he was sharing beers with First Minister Alex Salmond.
But for now he's talking about posing. His work for The Macallan saw the Trainspotting actor shooting with renowned American photographer Annie Leibovitz.
"I was nervous," he says. "She's this amazing talent and you don't know what you're getting into. It was nerve-wracking."
The night before, he'd been filming until 10pm and, on the day, caught the red-eye from LA to New York. "I had no sleep, was looking rough as hell and I walked into the trailer and Annie Leibovitz said, 'Oh my god, you look amazing, don't change a thing!'" he says, putting on an exaggerated Yankee accent. "I was like, 'Really? Jesus.' I was wearing a T-shirt with plane food on it."
Neverthless, the pair hit it off and the resulting pictures, portraying a smouldering McKidd, are nothing short of stunning. "I hate having my photograph taken – which is weird because I'm an actor. I get incredibly self-conscious. But she was amazing to work with and it was an honour to be photographed by a legend. I'm still pinching myself that it happened."
This is McKidd all over: a man genuinely appreciative of his opportunities, who takes nothing for granted – "because that's when things can go wrong" – and who even suggests he's still learning how to act.
"There's a lot I can improve on and I feel like I'm getting better at it. I'm always hungry to learn more and it might not always be there so you have to try to enjoy it when it's happening."
He doesn't resent the amount of publicity he's had to do lately which, with Brave and the new album, has been non-stop. "You get all talked out, get sick of the sound of your own voice, but when you're proud of projects, it's easier to talk about them."
He sees Brave as a personal triumph, having convinced the makers to let him do the voices of his characters, father and son Lord MacGuffin and Young MacGuffin, in Doric, but he's possibly prouder of the Speyside Sessions album, which he says has been "a dream come true".
"I'm a frustrated musician," McKidd says. "I've always had a passion for singing. If I hadn't gone into acting, I would've pursued something in the musical field. Sometimes I feel like I get more out of it than I do out of the acting. My dad has always said, 'That's where your real talent lies,' and I'd say, 'But Dad I'm an actor now.' So hopefully I've made him happier."
The album was partly inspired by his late grandfather, a "larger-than-life, natural entertainer" who was a fixture in Elgin's Bonnie Earl pub. "He's still talked about," says McKidd. "He used to sing bothy ballads to me when I was a boy. I vowed I would record him but I never got a chance."
A plan was hatched and for five days last New Year McKidd and his fellow musicians turned a rented house into a recording studio. "It was like a big week-long knees-up," he recalls. The album's success has caught the group by surprise and they've been approached to play concerts.
"It's hard scheduling-wise, but it would wrap the whole thing up quite nicely," he says. "It would be fun to do something at the Glasgow Royal Concert Hall."
McKidd is keen to get back on the stage, not just on Buchanan Street, but Broadway too. "It's been 10 years [since I acted in theatre] – too long – and eventually I'll be too terrified to do it. I'm very interested in doing musical theatre." But, he says, this will likely be in the United States, not here.
Likewise for any further singing endeavors. "It's funny because, in America, they're much more accepting of an actor who says, 'I want to do music now.' In Britain, there's a more reticent reaction to that, like: 'Who do you think you are? You are what you are and you can't be anything else.'"
It was being on the stage at the age of 10 that irrevocably changed the direction of McKidd's life. "I was going off the tracks a little, was in with the wrong crowd, getting in trouble with the police – not major stuff but definitely not being a pillar of the community – and I did a play and something happened. I was also painfully shy and it was the acting that got me over that and brought me on the straight and narrow."
He says it was his own motivation, rather than that of his parents, that pushed him into acting. "I went to see ET and that was a formative experience. I didn't know what acting was, I just fell in love with that film and it drove me to pursue it."
Playing Tommy in Trainspotting in 1996 may have been his big break but McKidd says he was immature in his early 20s and knew "in his gut" that a slow career progression would be his path – and he's always been comfortable with that. The turning point for McKidd was actually Richard Jobson's 16 Years Of Alcohol in 2003.
"Even though it was a low-budget film, I felt something change in me, in my attitude to acting and what I felt my abilities were," he says. "A lot of years doing low-budget films and theatre were distilled into that film." It was this, he says, that led to his acclaimed performance in the HBO/BBC series Rome.
His latest outing, Comes A Bright Day, is a return to low-budget independent film, McKidd playing the villain in a London-set crime caper.
McKidd has also gravitated behind the camera, having directed three episodes of Grey's Anatomy recently. He loves the challenge but admits he was terrified the first time. "The night before I started directing, I couldn't sleep a wink." The plan is to do more this season. "I want to keep going and see where it leads. I'd love to take those skills and try my hand at some kind of feature in Scotland," he says, hinting at a feature version of Macbeth – although he says that's a long way off – and a "Viking movie of sorts" with fellow Scots actor James Cosmo that would either be set in Scotland or use the country as a location.
Given McKidd's Hollywood success, his willingness to work in his homeland is encouraging. He hopes Brave has a positive effect on the country's film industry – in attracting big-budget Hollywood films to use Scotland as a location – but says what the Scottish film industry really needs is good writers.
"Everything starts from writing," he says. "Nurturing the writers to create more Scottish voices is the starting point. Some people say, 'We need a studio,' but actually, we need to get writers to write confidently in their identity, creating interesting, original stories."
McKidd is understandably vocal on this issue but when it comes to the question of Scottish independence, he is noncommittal. After taking a deep breath he says, "As an entertainer, I don't want to lay my personal beliefs out there because the point of actors is to entertain; we're not here to bang any drum. What I want is the best thing for Scotland – whatever that is – because I love Scotland.
"The Scottish people will know what's best. All I wish is for the Scottish people to be empowered and be happy. As long as that's the outcome, that's what I want."
It's a diplomatic answer for one who no longer lives here but McKidd visits Scotland frequently and has just returned to LA from here for the second time this year alongside his wife, Jane, and their two children, Iona and Joseph.
"The kids like to reconnect with their Scottish heritage and family, so we try to get back whenever we can to scratch the itch. Because I do get homesick."
It was hard when the family first moved to LA, he says, recalling how they missed home for a long time. "The kids love being at their granny and grandad's house, eating biscuits and getting spoiled."
His parents, he says, are proud of his success but, like him, remain unchanged by it. "They're still the same people and so am I. Well, that's how I see it anyway. But I think there's still shock that this wee lim from Elgin managed to do what he said he was going to do." n
Comes A Bright Day (15) is on general release now. For more on The Macallan Masters Of Photography series, visit www.themastersofphotography.com.