THE great musical divide of the 1950s was reduced to two names: Sinatra and Elvis.

Those Americans whose formative music years were the late 1940s simply loved the crooners, the immaculate articulation, the phrasing, the delivery, the image of sharp, crisp suits of wartime.

But the youngsters who grew up in the 1950s followed a new star. Elvis came along, all mumbly voice, shirt collar raised insouciantly and represented raw sex. The old guard liked to believe he had crawled out of a Mississippi swamp.

What if the music conflict wasn't just being played out in 1940s and 1950s America but the east end of Glasgow? What if two brothers were born with enough years between them to belong in opposite camps? That's the premise of actor Bill Paterson's new play, Astonishing Archie, which opens at Glasgow's Oran Mor next week.

"It's about a generational gap caused by the Second World War," said Glasgow-born Paterson from his London home. "Or rather those born before the war and those born afterwards; the baby boomers.

"I've always been interested in that gap, having experienced it growing up with my older brother, John. His lot grew up being Sinatra-type people, those who loved singers such as Nat King Cole who told stories in their songs, who had no time at all for rock'n'roll. And we grew up with Elvis and were madly excited by his music. The music lines were very defined, producing a gentle schism."

The gentle schism is heightened in the play (it first saw the light of day as a Stanley Baxter Playhouse on Radio 4) when two brothers battle over the music played at a funeral.

"It's not a profound piece by any means," says Paterson of his story.

"Really, it is essentially a play about the music of the period, and the music of Sinatra and Elvis is the device used to move the story along."

Does the play reflect the aphorism 'the boy of five is the man of 75', suggesting characters are formed during early experiences? And music plays its part?

"Yes, that's it exactly," says Paterson.

"These days the younger generation are formed differently with a pick'n'mix of influences, but not for us. And the enthusiasm in my life was perhaps set more strongly as a result.

"There's the added theme that life was easier for the baby boomers.

"No National Service for one thing. We got grants to go to drama college.

"We didn't have to leave school at 15.

"It's a pertinent subject, without hitting people over the head."

Paterson's arrival at Oran Mor has been talked about for several years, and it is certainly a coup for the lunchtime theatre, run by old pal David MacLennan.

"Dave asked me to do a play at Oran Mor and, as the theme worked as a radio play, director Marilyn Imrie encouraged me to extend the 30 minutes into a stage play."

The play also stars Kenny Ireland and Sharon Small. Richard Wilson was set to play the second Purgavey brother but a 'small operation in an artery in the neck' saw the One Foot In The Grave star surrender the role to Benidorm's Ireland, a long-time friend of Paterson.

"We've had to make a bit of adjustment because Kenny and I are the same age and he's had to age-up for the role, but that's all fine."

Paterson is clearly excited at the notion of appearing at Oran Mor. But he admits to being nervous. "I haven't appeared on stage in Glasgow for 30 years, since I appeared at the Third Eye Centre," he says with slightly dramatic voice.

Sharon Small plays Rev Margot Turnbull whose character has to mediate between the brothers.

"My role is to be the calm voice," says the actress seen most recently on BBC TV drama New Tricks. "I don't really show a great range in this performance, but I really love theatre in that it's so much about the emotion, the voice.

"Television just doesn't allow for scenes to be shot in sequence, and the acting is all very much done in short bursts. What I love about theatre is the chance to play out a story, get into a character. And once the play is completely inside me and I feel I've got the measure of the audience the theatre feels like a playground. It's fantastic."

Small admits the roles she plays can impact upon her own personality. "It can happen," she says. "When I appeared in Men Should Weep (at the National in 2010) although life was miserable for my character what I did take from her was that she was a bit more loving than me. I think during that run I became a bit more loving than normal."

Small is equally excited and trepidatious about appearing at Oran Mor for the first time.

"Rehearsal time is short," she says. "That means you have to be ready to go. But I've no idea what it will be like to step on that stage. For years I've wondered why I've never appeared in the A Play, A Pie and A Pint series and this is my chance."

She adds: "If you seem me at the bar and I seem very calm it means the minister has affected me."

Paterson won't reveal whether his stage brothers reach a reconciliation. "I don't want to give too much of the story away," he says with a wry grin, "but I will remind you that Presley and Sinatra were reconciled, when Elvis came back from the army. Sinatra, of course, had thought his career was being challenged by Presley but he later invited Presley onto his TV show and made up for the terrible things he'd said about him. Or, at least, it looked that way commercially."

And did he and his own brother make up? "Oh yes. But we both kept to our side of the music divide."

Astonishing Archie is on at Oran Mor, Glasgow, November 19-24.