Open-air Shakepeares are a summertime fixture on the theatre calendar, attracting picnicking audiences as much as midges. More often than not, such romps through the grass are frothy, heritage-industry affairs designed to be accompanied by strawberries and cream, and are not to be taken too seriously. But the Shakespeare's Globe Theatre company looks set to change such perceptions when it opens its outdoor tour of Romeo and Juliet in Glasgow next week as part of the West End Festival.

For the two young actors taking the title roles of the doomed lovers, it will also be something of a homecoming. Richard Madden and Ellie Piercy both studied in Glasgow before turning professional. Indeed, Madden has yet to graduate from the acting course at the city's RSAMD - and, as well as facing the pressures of playing such a meaty role in close proximity to the audience, will have the added anxiety of being assessed and graded by his tutors.

"This is the end of my third year," says Madden after a Saturday- morning run-through of the play. "Third year is based on productions anyway, so I'm being examined on this production in exactly the same way as I would be if I was doing a college production.

"The difference is that I get to work professionally alongside older actors, and get to observe how things are done and keep learning from that."

Despite being just 20 years old, Madden already has a strong track record as an actor, having previously taken time out from his studies to appear at the Citizens' Theatre in Franz Xavier Kroetz's play Tom Fool. Claire Lizziemore's production was such a hit that it transferred to London, where Madden was spotted by the Globe team.

Born and brought up in Elderslie near Paisley, Madden joined Pace, Paisley Arts Centre's youth theatre, at the age of 11, and notched up early appearances in the big-screen adaptation of Iain Banks's novel Complicity, alongside Jonny Lee Miller. Later he advanced to a lead role in a children's TV series starring Toyah Wilcox, My Barmy Aunt Boomerang. Getting to play one of the great romantic leads, though, is a big step up for Madden.

"He's such a complicated young man," he says of Romeo. "But it's quite good, and, because I'm young as well, I thought I wouldn't be able to play someone like him until I'd had some kinds of similar experiences. What I'm finding out, though, is that I can use my age to my advantage. He's still trying to find his place in the world, and is somewhere between a boy and a man. In terms of finding my place as an actor, I'm in that position as well. Romeo scares me and confuses me sometimes, because he's trying to find his identity. He really messes your head up."

The cause of much of Romeo's mental anguish is Ellie Piercy's Juliet. As a 26-year-old graduate of Rada who previously read cultural studies, specialising in English literature and theatre, at Glasgow University, Piercy is something of an older woman who readily admits that "Romeo is my toy-boy". Adding to her comparatively worldly-wise demeanour, she also points out that the last time she was in the East Quadrangle, where the performances are taking place, was during her exams.

While in Glasgow, Piercy's extra-curricular activities included an involvement with the Push Bar to Open theatre company, devising work with a young company that included a pre-Snuff Davey Anderson cutting his theatre-making teeth. Alongside Madden, Piercy also became involved in the early days of the now established Bard in the Botanics seasons of open-air Shakespeares, playing Helena in A Midsummer Night's Dream and having her first stab at playing Juliet.

"That was a different character then," Piercy says. "Now it's a different time, and for me it's a different story. I don't mean that to be in any way intended as disrespectful to Bard in the Botanics, but I was younger then, and hadn't trained as an actress. What I was learning then was about how to go deeper into an artform that you love. I was lucky then to be exploring site-specific work and all kinds of other things that have held me in good stead. At Glasgow I found the academic side of things quite hard, but I was so lucky getting to explore the things that I did. You can never get enough information."

How all this will translate into a new open-air Romeo and Juliet remains to be seen. Dominic Dromgoole, the artistic director of Shakespeare's Globe, has every faith in director Edward Dick and his young cast. In addition, he is not overly concerned with people having any preconceptions of the open-air production as "museum-bound Shakespeare-lite for the fizzy-drinks set".

"There's a very unwarranted Puritanism in English and Scottish theatre," he says, "that suggests theatre can't be something that's pleasurable. There's a sense of aggression against pleasure from elements that think theatre should purely be gritty and dour and instructive. I think that's nonsense, personally.

"Strawberries and cream are pleasant. Sitting on the lawn in the sun is pleasant, and I welcome that. So audiences can bring strawberries and cream if they want. As long as they bring whatever they bring in the spirit of pleasure, I don't mind." Romeo and Juliet is at the University of Glasgow East Quadrangle, June 19-24 (not 23), 8pm. There is also a 3pm performance on June 24.