SCOTTISH Borders Council prefers understatement to rippling prose. “The settlement is constrained,” declares its profile, “due to its proximity to the coast.” True enough. When the B6438 stops, you've arrived. The North Sea gives the road no choice in the matter.

There's farmland at your back, the national nature reserve and a Stevenson lighthouse to the north, and St Abbs wound around its harbour at your feet. The village is an interruption in a line of cliffs and craggy headlands, like a comma in a long sentence. The sea speaks for itself.

In summer you could believe St Abbs is a busy sort of place. That's a half-truth. The B6438 brings the trippers and the divers. Walkers follow the coastal path that rises on the heights above Coldingham Sands and finds its way to the reserve and a cacophony of guillemots and razorbills, puffins and kittiwakes. There are many more birds than there are people in St Abbs.

There are more houses, too, for most of the time, than inhabitants. Some visitors like the place so much they buy second homes for holidays and holiday lets. You can find that story repeated in any part of rural Scotland laying claim to scenery. In St Abbs, close to half the properties have gone, one way or another, to people who love the village but who can't – or won't – live through every season.

The community council reckons there are 123 adults and 16 children resident in The Shore, as they call it. That's an improvement on a decade ago, but, patently, few enough. In 1832, you're told, 16 families formed the community, with another 20 in Coldingham, a mile and a bit away. No one then called it St Abbs. At the nineteenth century's end a laird, the whisky-blending Andrew Usher, took a fancy to the tale of a castaway saint, Ebba or Aebba, and did away, officially, with “Coldingham Shore”.

On paper, the village is fragile now. Paper and ink don't always lie. In 2005, according to the community council's figures, there were just three children left year-round and 82 adults. St Abbs is the kind of Scottish village for which a local emergency self-help “resilience plan” seems apt. With one road for all weathers, one shop doubling up as a sub post office, and half the houses silent for much of the year, resilience is well understood.

The church that peers out over the sea is long since shuttered. The old primary school is these days – resilience in action – the Ebba Centre and cafe. What was the village hall is a visitor centre and there is a community trust dedicated to making St Abbs “sustainable”. Its triumph to date, against several odds, was in reclaiming the primary school building. None of this has been easy.

One you see past the picturesque, there's a thrawn pride about St Abbs. Some villages have it, some don't. When the visitors have gone and the weather is wild, you can tell yourself it springs from those generations of fisher folk, from that “proximity to the coast”. Perhaps.

Pride alone doesn't solve the second-home conundrum, or guarantee “sustainability” on the half-forgotten fringe of a sparsely-populated region. The question of what makes – or breaks – a community is never simple. What looks small enough from the outside is big and fundamental if it's part of who you are.

Where St Abbs is concerned, the Royal National Lifeboat Institution has overlooked that fact. It counts as irony. The RNLI depends as much as any charity on communities and their sense of themselves. Communities provide the volunteers for its 235 stations and its 346 lifeboats. Communities dig deep, year upon year, to provide the money - £51.15 million according to the 2013 annual report – to support the RNLI and ensure that crews have the gear they need.

From that attitude comes an ethos. The ethos brought the institution £118.75 million in legacies at the last count. Without communities, without what they are prepared to risk, sacrifice and spend, the RNLI wouldn't amount to much. The organisation knows this, counts on it, boasts of it. The mistake it is about to make at St Abbs flies in the face of the RNLI's traditions. Locals believe it also defies reason. And they call it a betrayal.

The lifeboat station on the Middle Pier at might not look like much, but it is part of the village's identity. There has been a boat ready to leave the harbour at any hour since 1911. Over the years, 227 lives have been saved by St Abbs crews. Thousands more – as the RNLI is first to admit – have been rescued. They are still being rescued.

The institution means to shut the St Abbs station by the summer's end. It intends to replace the inshore B class Atlantic 85 lifeboat, the Dorothy and Katherine Barr II, with a vessel based at Eyemouth. There will be new Shannon all-weather lifeboats for Seahouses and Amble in Northumberland, and a second inshore boat for Blyth.

The RNLI claims that alterations to the St Abbs station would cost £1.5 million. The crew say only a few bolts would have to be changed. The institution argues that it has a responsibility to use donations “appropriately”. Its own figures make you wonder. A new Atlantic 85 lifeboat is costed at £214,000; a Shannon at £2 million. Crew training is priced at £1404 a year; helmet, lifejacket and pager at just £678.

The St Abbs crew are specialists, locals – often from the redoubtable Crowe family – with local knowledge and the medals to prove it. The seas off their coast form one of the most popular diving areas in Britain and their speed of response cannot, they insist, be matched. At the end of May, hours after a village meeting, the St Abbs boat was in the water within four minutes to rescue a diver in the difficulties. It's what they do.

Why they do it is another matter. In 2011, Darren Crowe added to the St Abbs collection of medals after a fisherman slipped and fell from St Abbs Head. The visitor wound up in a cave at the foot of the cliff, clinging to a rock, the tide rising. Mr Crowe swam through a fissure and brought the visitor out. The RNLI gave the St Abbs helm a gallantry medal.

There are a lot of posters up for the sake of the lifeboat. Four dozen MPs, thus far, have signed an early day motion. There have been protest marches and meetings, backing from the National Trust and the Scottish Sub Aqua Club. Gala Day money that in any other year would go straight to the RNLI has been given to Save St Abbs Lifeboat. The institution refuses to budge. The closure, it says, will go ahead.

Behind the anger there is bafflement. The RNLI, of all organisations, seems deaf. You hear it repeatedly: the lifeboat is the heart of the community. That word again. It can mean nothing or it can mean everything. What St Abbs knows for sure is that, once gone, a community's sense of itself cannot be restored.