As the 16th annual Westival gets underway, festival goers old and new descend on Gladstone Heritage Village in Western Australia and immediately settle into their rival camps: Aboriginal and Morris dancers, punk rockers and ukulele players, winos and musos. Among them are pretentious theremin technician Roland (Robert Sheehan), an Irish dog-washer making his Westival debut in the small workshop hut, and folksy fiddler Keevey (Rebecca Breeds), a seasoned pro who tours with family outfit The Warrickins. Following an ampli-frying duet in which Roland recognises latent talent in Keevey, their mutual attraction threatens to give way to unrequited admiration when he inadvertently criticises her folk rock roots.

Ben Elton’s first film since Maybe Baby in 2000, after which he moved to Freemantle, Western Australia and gained Australian citizenship, Three Summers draws from his experiences of nearby Fairbridge folk festival and presumably his marriage to a bass player to tell the story of a fictional festival. While ostensibly a romantic comedy, and despite the writer-directer’s assurances to the contrary, the film — like Elton’s early work — is also a thinly veiled political satire, this time challenging Australia’s mistreatment of its original and refugee populations. The audience’s introduction to Westival, via Queenie’s (Magda Szubanski) regional radio show Festival Folk, begins with an acknowledgement of the Aboriginal tribe and their claim to the surrounding land.

Subtlety may not be Elton’s strongest suit but ensemble comedy surely is, and for Three Summers he has lined up some real headline actors — Szubanski included. Highlights include Adriane Daff as Diamond, a prog-rocker who reworks Australian classics (“Cry, Kookaburra, cry”) while campaigning against the tampon tax; Kate Box as Linda, a despotic security guard who requires young patrons to provide two forms of photo-ID; and Deborah Mailman, an Alcoholics Anonymous councilor who is left to work out of a disused bar that still receives accidental deliveries of beer. Of the supporting cast members Kelton Pell and Michael Caton get the most to work with as tribal leader and Morris dancer respectfully, their antagonism producing many of the film’s most pointed and poignant moments.

Protagonists Roland and Keevey have their share of differences too, though their disagreements are mostly limited to the world of music — though the question of heritage does crop up when the latter is required to justify her Irish birthright. Sheehan — by now a festival favourite, with films The Messenger, The Road Within and Jet Trash having appeared in programmes past — remains as charismatic as ever, delivering another live-wire performance that is as kinetic as it is compelling. Techno Folk Funk might be a non-starter but at least the theremin has finally found its Brian Wilson. Breeds, meanwhile, charms in her first leading role, having left Home and Away in 2012 to appear in the likes of Pretty Little Liars and The Originals. Her relationship with her alcoholic father (John Waters) is superficial but nicely played.

Likable and well-observed, Three Summers could have easily sustained itself on folking puns and effortlessly endeared Elton to his new compatriots. That it attempts to address issues of inequality and injustice and risks alienating more than just the ukulele players in the audience is to the film’s undeniable credit. It’s Australia in a tent, expertly pitched.