Charley Pride, one of the towering voices of popular country music over the past half century, is contemplating why he's never had much of a knack for song-writing.

Pride's biggest hits - among them Kiss an Angel Good Mornin', Is Anybody Goin' to San Antone, and Wonder Could I Love There Anymore - have invariably been penned by others.

"The lyrics are what makes a great country song," he says, launching directly into the first verse of Kris Kristofferson's Loving Her Was Easier by way of example. "You see, to be a great songwriter you have to use the least amount of words to make your statement, and I'm terribly long-winded."

It's true. Pride can yakety-yak with the best of them, but then he has plenty to talk about. The 77-year-old, who plays Glasgow next week, happily runs through the bullet points of a stellar career. The star on the Hollywood Walk of Fame "between Gladys Knight and Leonard Bernstein"; the three Grammies; the 30 Country number one singles; the membership of the Country Music Hall of Fame. "I'm in there with Johnny Cash, Tammy Wynette, Conway Twitty and George Jones," he says. "We all started out together. The sad thing is that they're all gone and I'm still here, but I guess that's a blessing, too. He could have taken me like He took the others."

One significant fact differentiates Pride from his dear departed country contemporaries. Here was a black share-cropper's son from Mississippi who succeeded in carving out a career at the forefront of America's most notoriously conservative musical genre at a time when the Civil Rights movement was still mobilising against severe racial discrimination. Pride insists that he has never suffered any form of prejudice or cat-calling over his colour in the 50 years he has been performing, and immediately notes my scepticism.

"I say that and you give me that, you-gotta-be-lying look!" he laughs. "But it's true. Back when I started I used to be the opening act on package shows with people like Merle Haggard and Buck Owens, and promoters were a little sceptical about booking me. Backstage this guy was worried that I would come out and people would be a bit shocked, so my manager and I came up with an introduction. I said, 'Ladies and Gentleman, I realise it's pretty unique me coming out here playing country music wearing this permanent tan, but I hope you like my songs!' I decided I had to say exactly what they were thinking, you see, and then hit them with the music. When they heard my voice they didn't care whether I was pink or green, and it's been that way for the past forty some years."

Whatever the struggles he may or may not have faced, Scotland has always been a happy hunting ground - though it's not clear whether he's aware of our own Sidney Devine's rendition of Crystal Chandeliers, one of Pride's signature songs. "I've been coming over here since my very first top ten record, which was Just Between You and Me in 1966," he says. "In the early days I was told that Scotland and Ireland were very strong for country music, people would say, 'Oh man, they love you over there'. You hear that kind of stuff all the time, but when I got over here, boy, I found they were telling the truth. From the very beginning I wanted to be an international artist, and Scotland has been a beautiful part of that."

Even if he has been married to the same woman for almost 60 years, a life such as Pride has lived is rich in cinematic promise. A film biopic has been in various circles of development hell for over a decade. One name in the frame early on was muscleman Dwayne Johnson, aka The Rock, but now the spotlight has moved to David Oyelowo, fresh from the triumph of portraying Martin Luther King in Selma.

"David Oyelowo is going to do it now," says Pride. "We're supposed to see the script on May 27 and I hope we get something going." He has high hopes. "Every artist where they've done a movie of their lives, be it Johnny Cash or Ray Charles, there have been Oscars involved. The difference here is that I'd like to see it. Unlike my friend Johnny, I'm not planning on watching it from beyond the grave. I want to be part of it. In fact, I'd like a little cameo. I could take Charley Pride to the airport!"

He has, he says, no thoughts of retirement. Though he recently underwent an operation on his vocal cords, Pride says happily that "my fans think I'm singing better now than I ever did, and I still love singing for them." He's clearly not a man who spends much time resting on his laurels or luxuriating in nostalgia. He says "my favourite song is always the one I'm singing at that precise moment. I sing everything in my show as though it was my biggest single." Ask him to look back at his career and pick out the peak and he laughs. "Oh, it's been wonderful, but I don't think I'm at the top - yet!"

Charley Pride plays Glasgow Royal Concert Hall on Wednesday May 6