There is a joke doing the rounds on the internet that originated in America.

It is about a man waiting in line in a grocery store behind a woman, who is speaking on her mobile phone in a foreign language. Once the woman has finished her call, the man approaches her and points out that, as she is in America, she would need to speak English.

"Excuse me?" says the woman, before the man very slowly, as if talking to a child, suggests to her that if she wants to speak Mexican, then she should go back to Mexico. To stress his point, the man points out that the woman was in America, where they speak English.

"Sir," says the woman. "I was speaking Navajo. If you want to speak English, go back to England."

Despite its locale, this joke seems to be the perfect illustration of the themes behind this year's Mayfesto, the Tron Theatre's annual look at politically-tinged drama, which this year themes its programme around the all-too-timely notions of Colonisation and The Spoken Word. Nowhere is this theme found more readily than in Mayfesto's two flagship productions, which find Tron artistic director Andy Arnold directing Shakespeare's The Tempest, while Communicado's Gerry Mulgrew oversees Timberlake Wertenbaker's Our Country's Good.

Produced in association with the Royal Conservatoire of Scotland and featuring international casts, themes of colonisation are apparent in both plays. In The Tempest, Prospero's enslavement of Caliban is to the fore, while Our Country's Good focuses on prisoners in an 18th-century Australian penal colony where inmates create and perform a play.

Elsewhere in the programme, the Imaginate festival tours Saltbush, an Australian/Italian co-production that looks at a journey made by two Aborigine friends. Also featured is the Tamasha theatre company, which presents My Name Is ... and dramatises the real life plight of a 12-year-old girl who fled Glasgow with her Pakistani father. Heart is a production by the Zendeh company, which dramatises a love story set between Durham and Tehran in 1953.

As well as these full productions, Mayfesto will also feature debate, plus a series of rehearsed readings. Many of these will feature the work of Aime Cesaire, the Caribbean-born author whose own version of The Tempest looked at the story through the African-American experience of colonialism.

"Mayfesto is a season of works that questions and challenges things, both in terms of artistic work and ideas beyond them," says Arnold, "and what motivated me for Mayfesto this year was that we are building up to this huge great celebration of the Commonwealth through the Commonwealth Games. With that, it seemed the right moment to question the whole basis on which the Commonwealth was established in relation to slavery and so on.

"Coincidentally, I had been talking top the RCS about doing a classic piece, and that is why I thought of doing The Tempest, but taking a different slant on it, heightening the colonial elements that are in it. It has always been a colonial play, but in this production, Caliban is very much played as someone with great dignity and who has a certain moral authority in the piece, and that makes it a very appropriate piece."

Arnold has also opted to open and close the play with words by Cesaire, who, as well as a life's work as a writer, thinker and activist, taught radical thinker Frantz Fanon, who, like Cesaire, was born on the island of Martinique.

"Cesaire has become an important part of the festival," says Arnold. "When I thought about looking at colonialism in Mayfesto, I knew I wanted some kind of staging of Cesaire's epic poem Return To My Native Land, which I have had on my bedside table, as it were, since my student days. It is a really powerful, visceral and beautiful poem to stage, so I knew I wanted that to be part of Mayfesto.

"I was not familiar with Cesaire's other work, although I had heard of A Season In The Congo from a production at the Young Vic. Then I found out he had done his own version of The Tempest, called A Tempete, in which Caliban is more of a freedom fighter and Prospero is a white slave trader. There is a beautiful prologue and epilogue, in which Caliban has the last word, so I have topped and tailed this production with Cesaire's words, as well as programming readings of these other pieces as part of Mayfesto as a homage to this great unsung writer."

Like Shakespeare and Wertenbaker, Cesaire was an artist whose work had politics bursting through every line without the issue ever having to be forced.

"I have always steered away from didactic theatre," says Arnold, "but there is nevertheless a need for issue-based theatre. For many years people shied away from it, but I think it is possible to marry good artistic writing to something that is inspired by political issues. Sometimes people have got away with it because it has been about a worthy cause and has just been speaking to the people who want to hear these things, but looking back over the decades, the best political play I have ever seen was Brian Friel's Translations, and that does not have a line of politics in it."

While The Tempest and Our Country's Good certainly sit alongside Friel's play in that respect, the rest of the Mayfesto programme is invested with equal weight.

"Mayfesto's changed," Arnold says. "When we started, it was pretty much all full productions. Now it has become more of a focus for workshops and debate. It is a great platform for artists to interact, so there might only be 60 people watching something, but they will be in the bar afterwards talking about it. It is interesting, because if you see a full production, you leave the building straight afterwards, whereas if you watch a work-in-progress piece, because it is not finished, there is this assumption it is up for discussion, and that you as an audience member might be able to influence how it develops. That is happening a lot.

"Rather than scratch around for a company from down south, we can put on something from scratch and see how it develops."

Mayfesto 2014 is at the Tron Theatre, Glasgow, today until May 31.