The brightest moment of my visit to the 24th BFI London Lesbian & Gay Film Festival was undoubtedly Ander. Roberto Castón's unassuming portrait of repressed homosexuality is nestled snugly in the beautiful Basque countryside, arriving firmly grounded in reality and riddled with traditional Spanish flavour. When listening to a filmmaker talk about his own work it's always worth having an eye-brow firmly cocked, and when writer and director Castón arrived before the screening to talk of his film's "honesty" and "characters that resembled real people," I took it all with a pinch of salt. But, just a few minutes after the projector began to whir I was completely convinced. The people and places in Ander hit a perfect note of realism which speaks to the viewer's experiences more than the raw vérité of documentaries ever could.

Couched in the setting of the BFI's festival, it was obvious that Ander would deal with gay issues, but for the first third there's no real indication of any kind of homosexual theme. Much of this initial portion is used to establish our titular lead, Ander – his home-life, his sex-life, and his personality. He is a balding forty-something farmhand and factory worker who lives with his aging mother and soon-to-be-wed younger sister. On first analysis, his comings and goings sound like intensely boring cinematic fare. Ander is a man lacking the intimacy of a good woman, but is otherwise surrounded by people who love and care for him. He is often in the company of friends, be they his over-bearing and over-caring mother or course pal Iñaki – who endlessly encourages Ander to join him on excursions to the village prostitute. Despite his comfortable environs, there's a frustration bubbling under the surface that stops the action from becoming so relaxed that it turns stale.

The success of this balancing act owes a lot to two particular actors. Joxean Bengoetxea is a quiet marvel as Ander, never extending himself into the all-to-often plumbed depths of cinematic exaggeration. He manages the tricky task of adding a tinge of unease to his very real and likable performance. Yet the real star of this first third is Pilar Rodríguez, putting in a surprisingly brilliant comic turn as Ander's traditionalist mother. Her portrayal deploys one of cinema's most potent weapons, speaking to the lives of the audience without betraying the wholeness of her character. She never drops the facade of a matriarchal Basque mother, but her disproving glances and off-hand un-politically correct comments are the perfect mirror for mothers and grandmothers the world over. Her comic talents are kicked into overdrive by the appearance of the film's chiseled Peruvian macguffin, Jose. After Ander falls and breaks his leg, the quiet itinerant farm-hand arrives to pick up the slack on their small family farm. Jose (Christian Esquivel) is just the kind of dubious foreign interloper of which Ander's mother is immediately suspicious. The fact that they do not share a common language (she speaks only Basque, not Spanish), makes their awkward dinner table interactions all the more hilarious.

That dinner table is the centre-point for many of the film's early scenes, bringing together all the major players in one neatly composed space. It is also the best canvas for director Castón to display his talent for mis en scène. The composition of the dinner table is masterfully marshaled, down to the placement of each knife & fork. The audience view the scene from one end, as if we are sat within the television set Ander occasionally operates to deflect awkward conversation. The comfortable but realistic setting, subtle comic performances, and wonderful scene construction all come together in these early moments to create some of the most joyous cinematic cocktails Ander has to offer.

Jose's arrival is the catalyst for real narrative progression, which extends so well from the measured – but not languid – opening third. His sharp hispanic jaw-line and shirt-off manual labour awakens a latent homosexuality in Ander. Still hobbling around on crutches, he begins to follow Jose as he moves around the farm. This is ostensibly to ensure his work is up to scratch and to relieve the boredom of a broken leg, but as the pair spend more and more time together, a burgeoning friendship quickly begins to morph into something deeper and more dangerous. At this point, Ander skirts a little too close to ponderous, as the slow pacing of the first portion continues unabated. Luckily, we are pulled back from the brink by the inevitable boiling over of sexual tension.

All that repressed energy our lead has held back is suddenly unleashed. Ander could never be accused of moving at speed, but the emotional ups and downs start to flow beautifully from one pivotal scene. The film even manages to move seamlessly into a heart-rending sub-plot and back, without becoming emotionally overbearing or disjointed. The still-injured Ander finds himself thrown into a maelstrom of sexual confusion, not least as he is still dabbling with the local whore. Even Jose gets involved in the heterosexual activity, adding to the swirling confusion Ander suddenly feels around him. His reaction to this uncertainty is predictable, but in the way that the behaviour of a friend might be foreseen, rather than the step-by-step boredom of a formulaic plot. To keep us from getting too bogged down in Ander's soul searching, Castón suddenly turns the prostitute Reme (Mamen Rivera) into a fully functional character. Her woeful and redemptive travails provide the film's final third with its major narrative push and, while not as gripping as the rest of the action, are still intriguing enough to keep things ticking along nicely. As we approach the climax, Castón also begins to slowly tie up the various sub-plots that have trickled along in the background. It's a credit to the pure realism of his story that these extra narratives do not feel like intertwining threads, just a part of the natural progression of linear time. Amid these various ancillary activities, Jose and Ander's relationships is still the core of the picture and its resolution marks the end of the whole piece. The warm and satisfactory ending maintains the film's admirable ability to make scripted activities feel like they are happening in the real world.

Ander is a fantastic film, which acts like an reserved drama but packs a big punch, thanks to stellar work from a predominantly Basque cast. Roberto Castón's simple camera-work and excellent scene construction wonderfully compliment his story of repressed gay love in an area of the world rarely captured on camera. Ander has not yet achieved a cinematic release in the UK, but has been making the rounds at various festivals. Cinema-lovers should keep their fingers crossed that a distributor picks up this gem, along with maintaining a beady eye on local film festival schedules. If you get the chance to see Ander on a screen of any size I recommend that you leap at the opportunity.