Riding the wave: Finisterre has become the favourite brand of discerning surfers by prioritising ethical standards over ever-changing styles

Ethics and the environment (not to mention the lure of the sea) are more pressing concerns to the team at Finisterre than any vagaries of fashion – it even sources wool from its own flock of sheep. But that hasn't slowed its advance as the most coveted surf brand around.

There's a lot about Finisterre that seems too good to be true. The British surf-clothing company, proud owner of a stack of ethical and environmental awards, has a sickeningly wholesome image. With product descriptions that read like Greenpeace guidelines and a website full of lifestyle photos of the team (plus dogs), smiling and leaning against a battered Land Rover, it all looks alarmingly idyllic.

So when I arrive to spend the day at their "office" – a trendy warehouse perched above the Cornish seaside town of St Agnes – I have high expectations. Surrounded by stacks of surfboards leaning against the walls, their dog Happy (an excitable half-husky, half-beagle) curled up on the sofa and hot pasties from the local café for lunch, it is clear that their work-life balance really is hanging in enviable equilibrium.

"We could grow into a big multinational, but we like being here and we like our lives," explains the company's founder, 34-year-old Tom Kay, whose joined-up freckles, receding white-blonde hair and Milky Bar Kid enthusiasm make him seem straight out of a wholesome 1970s surf film. "On an average day, anything can happen. If there's surf, we'll go for a surf. There are no set hours, so people come and go as they want. It could probably be more efficient, but it's good this way."

Finisterre specialises in making a select range of environmentally friendly technical clothes from recycled or natural fibres, such as merino wool. But at the heart of the company ethos is a desire to make clothes that last. "There are lots of surf brands out there making really crap high-street stuff," says Kay. "We want to go back to making the kind of jacket your dad still has after 30 years. Yeah, it might look a bit tired, but he still likes it and it still works. We don't want that cycle where you get rid of stuff quickly. We want people to keep our stuff for a long time."

Yet, despite this apparent lack of interest in being in fashion, their plain, subtly branded clothes have become achingly fashionable in the surfing world. They even have a top-10 big-wave surfer, Carlos Burle, on board as a brand ambassador. The Brazilian, who has been seen standing on some of the most fearsome waves on earth, could have been sponsored by any of surfing's giant brands for millions of dollars, but instead chose Finisterre. "He didn't want just another sticker on his board – he wanted to be involved in something bigger than that," Kay explains.

Seven years ago, Kay left a "very London" corporate- property job to come to St Agnes. He set up Finisterre in a back bedroom while working part-time as a lifeguard and surf instructor. Producing rugged fleeces for sailors and surfers, he soon realised there was a market for hard- wearing clothes that bucked the trend for disposable fashion.

Now perched in his office on an old dentist's chair, defying the freezing rain outside with bare feet and cargo shorts, Kay seems to be keeping warm by jumping up and down in an eco fervour. "We haven't deviated from our original brand idea," he gushes. "People have said, 'Take this money and get loads of T-shirts made in China,' but we wanted to take one thing and do it well."

Finisterre's building sits on a road opposite Surfers Against Sewage, the tub-thumping environmental charity whose unusual campaign tactics have attracted mass support on green issues among the surfing fraternity. Indeed, over the past few years, the green movement has rocketed among British surfers. New environmental events are cropping up all the time, the most recent addition being Chicks With Sticks, a women's eco surf day in Newquay next month. Now Finisterre is helping to lead the charge for surf brands, making clothes that are desirable without being throwaway or too damaging to the environment.

Just back from visiting its factory in Portugal that morning, designer Debbie Luffman, 28, has a pile of mending next to her desk. It seems odd that one of the product designers is also working part-time to repair customers' clothes (especially when the firm often doesn't charge for the service), but it's all part of the company ethos.

At the top of her mending mountain is a blue raincoat with a series of twisted snags on the sleeve. "This one went under a train somewhere east. I think it was Kazakhstan. We'll just sew a patch over and it'll be fine," explains Luffman. "We don't want to be a fashion brand like Billabong or Quiksilver. All our clothes have a lifetime guarantee; it's not about seasons or trends. If it breaks we'll put a patch on it; it's a badge of honour that shows your jacket has been-there, done-that."

Finisterre's production line is squeaky clean to the point of parody. So much so that I struggle to keep a straight face when I'm told that one coat is made by a social regeneration project run by nuns for the disadvantaged in Colombia, using the world's first closed-loop polyester recycling scheme.

Their latest venture is an attempt to locally source merino wool. The feat was previously thought impossible as the sheep have never flourished in the UK. Then Kay found the world's only remaining flock of Bowmont sheep, a hardy cross-breed created as a way of farming the wool in Britain.

He invites me to pay a visit to Westcott Farm, which lies down a cow parsley-lined single-track road in nearby Devon. Lesley Prior, 53, bought the final pure flock of Bowmont sheep from the researchers in Scotland who had invented the breed 25 years ago. By crossing British White Shetland sheep with New Zealand Merinos, they were able to create an animal that produced merino-soft wool but was hardy enough to withstand UK weather. Their wool, which is drying on Prior's battered oatmeal-coloured Aga, is so soft that I discover I am still inadvertently stroking it 10 minutes after it's handed to me. "The Finisterre team are encouraging me to breed them as fast as I can," says Prior. "They are getting a guaranteed English product and I'm getting a way of keeping the breed going; it's worked out brilliantly."

While the flock is still relatively small, Finisterre will be using the wool in its socks, beanies and other accessories, with the wool for its T-shirts and jumpers still coming from Tasmania. But it hopes that within a few years the yield will be big enough to use it for its full range of merino gear. Unlike petrochemical-based man-made fibres, which are most commonly used to make breathable sportswear, merino wool naturally takes moisture away from the skin and isn't made using polluting chemicals. Merino also has natural properties that make it antibacterial and warm when wet, which can't be mimicked successfully with synthetics, and make it ideal for use in the sea or the rain.

Back at Finisterre HQ, the plan was to go surfing; insistent rain and lack of waves mean Kay is enthusiastic about picking a spot to go paddling instead. "How about the caves over there," he suggests, pointing at some rocky outcrops several hundred metres out along the pancake-flat sea. We wetsuit up and jump on our boards, much to the bemusement of locals who titter at the millpond we're venturing on to.

Paddling fast out into the ocean, Kay shouts over his shoulder, "When the tide's right you can paddle right through these caves. It gets really dark, but it's fine." Beginning to get slightly jittery, I follow along behind, watching the shore slip further away over my shoulder. We were half way into the cave before Kay said the tide was too high to venture further. I couldn't pretend I wasn't a little relieved.

Back on shore I make a beeline for the car, specifically the lure of its heater and a flask of tea. Saying goodbye to Kay, I thought he would be on his way back to the office. But instead he returned from his car with a pair of goggles and neoprene Balaclava. "Might as well go for a quick swim," he says, as if to prove he really is living the lifestyle, before sploshing back through the rainwater and into the icy sea.

For more information, visit www.finisterreuk.com