Why is a famous heterosexual love story the centrepiece of this year’s Glasgay?

If YOU want an idea of the philosophy that drives the annual Glasgay! festival, just look at this year’s centrepiece production. Say what you like about Harold and Maude, the cult 1971 movie adapted for the stage in 1980 by original screenwriter Colin Higgins, but by most definitions, it isn’t a gay play at all.

True, its author was a gay man whose humanitarian foundation still gives out Youth Courage Awards for “bravery in the face of discrimination, intolerance and bigotry”, but Harold and Maude’s love story is a straight one. What makes it interesting is that Harold is a morose young man barely out of his teens, while Maude is a go-getting optimist nearing her 80th birthday.

The reason it appealed to Glasgay! producer Steven Thomson, when Theatre Jezebel’s Kenny Miller mentioned he was interested in directing it, was the story’s rejection of society’s sexual norms. If two consenting adults are attracted to each other, goes the thinking, what should it matter that there’s a 60-year age difference between them? In this way, the festival’s message of tolerance applies to heterosexual behaviour just as much as it does to the lifestyles of lesbian, gay, bisexual and transgender people.

“Maude represents a place we all want to arrive at,” says Thomson. “She stands for free love – liberated, evolved, cultured, sophisticated and worldly wise.”

It’s an attitude that helps account for Glasgay’s rise from its humble beginnings in 1993 to today’s 20-venue jamboree that routinely plays to 35,000 people. The LGBT experience is still central, of course, but this is a mainstream festival that goes beyond niche appeal.

But does putting on Harold and Maude in a gay festival throw a different meaning on it? “Kenny would say no and I would say yes,” says Thomson. “It opens up contexts and ways of doing the work. It’s a way of drawing an audience in to think differently. Glasgay! is about all of these intersections. We’re emerging into this so-called evolved society where equality is supposed to mean more, but we’re still coming across a lot of barriers. All of those barriers are very visible here – they’re barriers that prevent Harold finding himself.”

For his part, Miller was keen to get involved in Glasgay! again, even though, like most artists, he does not choose work in order to speak out about his sexuality. Harold and Maude was simply a play he wanted to stage, primarily because of its portrayal of such an uncommon romantic relationship.

“I like to be seen to be doing different things and I’ve never done a play where the central character is a woman of that age,” says the director and designer, who has cast Vari Sylvester and 21-year-old Tommy Bastow in the lead roles. “Doing the play, I’m asking, ‘At what point does he find her sexy?’ When he first meets her, he just thinks she’s this mad woman, but through their relationship, he becomes sexually attracted to her. His decision is completely based on love.”

Harold and Maude is a classic role-reversal comedy. Here, the younger generation is stuck-up, repressed and, thanks to Harold’s obsession with suicide, not a little warped. It is the older generation, in the form of Maude, that is free-wheeling and full of hippy idealism.

“It’s important to her that she’s free,” says Miller. “She sees that he’s not free in his life in any way whatsoever and she wants to liberate him from his mother, his background and his wealth.”

What’s revelatory to the director is how much the play makes him question his own values: “If I found out my 18-year-old nephew was suddenly having sex with a woman who was 79, how would I react? I have to say I would be quite shocked. If my mother was still here and I found out she was sleeping with an 18-year-old boy, I would also be shocked – in the same way that some parents would be shocked if their kids came out as being gay. That’s why I want to do it because I don’t think it’s right that I should be shocked by it. I don’t think there’s anything wrong with two people falling in love.”

The production also fits in with a theme running through this year’s festival to do with acts of union. At a time when churches are debating same-sex unions and politicians are contemplating the future of the union between Scotland and the rest of the UK, it’s an idea with repercussions everywhere from the home to civic society. Thomson hopes his programme, which ranges across the arts, will make us consider whether we are wedded to the past or ready to break free of the old stereotypes.

In the case of Harold and Maude, the unconventional relationship is personal more than political, but it has broader repercussions too. “I went back and looked at the movie more carefully,” says Thomson, “and there’s this one great line where she says, ‘What use borders and nations, I miss the kings.’ In that respect, Maude represents the liberated nation state.”

If Scotland turned out to be such a place, there would be a lot of questions we would have to ask. In a newly independent country would laws have to be rewritten? Would we legislate against hate crime? Would we find it acceptable for church leaders to make homophobic comments?

Thomson sees it as important that Glasgay! addresses such questions in order to keep socially relevant. It’s why the theme of union is all over this year’s programme in events such as Unit-E, a group show at the Virginia Gallery; Dustin Lance Black’s 8, a rehearsed reading of a courtroom drama about the same-sex couples who challenged California’s anti-gay-marriage law; and I ♥ Alice ♥ I, a two-hander from Dublin’s HotFor Theatre about a long-standing lesbian relationship.

“The underlying theme of questioning acts of union is about the political climate we’re in and the fact that the equal marriage debate is happening at around the same time,” says Thomson. “We’re all evolving and changing.”

• Glasgay! is at various venues, Glasgow, 15 October to 4 November; Harold and Maude is at the Tron Theatre, Glasgow, 30 October to 3 November.