There's a very quiet commotion going on in a rehearsal room in Glasgow's west end. Birds of Paradise, the "inclusive" theatre company, is holding a photo-call for a new production, Mouth of Silence, which, on the 10th anniversary of Guatemala's liberation, looks at the civil war that tore the country apart.

In Guatemala, 22 languages are spoken - and, as you can imagine, in any sort of negotiation things tend to be lost in translation. Here, in Glasgow, sign language is also being used to allow the company to communicate with signer and actress EJ Raymond, who is deaf. In addition, there is a telephone call about the school visits that accompany Mouth Of Silence. It's to do with a phrase that appears on the show's flier, which the young people don't understand. What does it mean, they want to know, when it says that the production will be "inclusively signed"?

"Language," says poet and Mouth of Silence writer Gerry Loose, "is a huge issue. Or rather, the control and use of language is a huge issue. It's about who uses the language and who controls it and in what way, who uses it to become the dominant force. You can see that in Guatemala, where, with 22 indigenous languages, you're constantly needing an interpreter and the full opinion never really gets put out there. It's always deflected and dissipated by the linguistic manipulation of whoever's in charge. So, if there are 22 languages, who are you going to speak to to get the real lowdown?"

Given the many complexities of Guatemala's past, it's interesting that those in control of the history books aren't making more of a song and dance about the anniversary. Even during the rise of global activism in the 1980s, Guatemala was left to get on with it, and became something of a forgotten, if not lost, cause.

Birds of Paradise artistic director Morven Gregor says: "Guatemala is a relatively small country, and has always been overshadowed by other events, especially after the horror of Rwanda. But, even in the 1980s everyone knew about Nicaragua and El Salvador, Argentina or Brazil, but not Guatemala.

A lot of that was down to America being such a player in what happened in those countries, whereas, in Guatemala, it was their own government who was doing it. People ended up having to live in exile for 15 years, and the play looks at what it's like to go back."

Mouth of Silence, though, categorically isn't a polemic. "That's very easy to do," Loose shrugs, aware, too, of how language can be abused at the other end of the political spectrum. "But I'm never convinced by stories that are introduced to reinforce an agenda. You make it personal, and look at a small group of individuals over time. It's a well-trodden path," he points out.

Loose stresses the solidarity and historical parallels between Guatemala and other countries. When he visited Sudan, for instance, he witnessed first hand "an indigenous people who have very little grasp of the alleged official language of the alleged official country in charge - China. I've also seen it, curiously enough, in the United States. In Mexico, in the Chihuahua desert, one step up from the bottom of the heap are the Spanish-American speakers, while on top of the pile are people who speak English, and who use it as a tool to put people down."

According to Loose: "The parallels in Scotland are quite clear. It's often said to be a nation of three languages - Gaelic, Scots and English - but it's English that's in charge, if you like, and huge amounts of Scots and Gaelic speakers are marginalised. There are, of course, other languages that are hidden, as they are in Guatemala. For instance, there are more Urdu speakers in Scotland than there are Gaelic speakers. When you think about that it puts things in perspective, so the prime concern for me is to bring out not just the politics of language, which is a subtext within it, but to give the protagonists within the play an active voice given that subtext."

This is all quite ambitious for Birds of Paradise, the 12-year-old company taken on by Gregor a couple of years ago following a period in which the company was run without an artistic director.

Since her arrival, an ambitious programme of work has included last year's Brazil 10, Scotland 0, a forging of ties with the RSAMD, and a new scheme, Agents of Change, which advocates a voice for inclusion in a mainstream arts network.

"In 20 years," Gregor maintains, "inclusivity shouldn't even be an issue. It's taken one of those funding dances to be where we are now, hopefully producing one national tour a year. We're interested in using voices that are often ignored, and we can do anything."

As if to prove it, Mouth of Silence is set to be performed outdoors, in The Hidden Garden, a city retreat behind Tramway. The setting ties in with Loose's poetry, which is influenced by the environment. Working in a manufactured rural setting at the heart of a former industrial and otherwise urban space is a delicious contradiction which Loose relishes.

"I don't see the different areas of my work as distinct from one another," he asserts, "because the determination of power structures and language have a precise and exact parallel with the power structure of who owns the land. Who controls the language also controls the land, and culture, horticulture and agriculture are not distinct. That's the pillar on which my work stands. Also, building gardens is creating something that is positive and peaceful, and is a clear statement that there is an alternative. That's what the play's saying: that there's a real alternative to conflict, there's a real possibility to end armed warfare. The alternatives are there, and that's all tied up in how language is used."