THE plume of white smoke rose so high it could be seen fully 30 miles away.

As firefighters tried, in vain, to save the biggest building on Scotland’s most remote inhabited island - wildlife photographer Rob Fray watched swirling clouds billow on the horizon.

Mr Fray was on Shetland, in the car park of the Sumburgh Hotel. The blaze was on Fair Isle, nearly three hours south by ferry. “The Obs is on fire,” Mr Fray tweeted on Sunday afternoon. “Heartbreaking.”

The Obs - the Fair Isle Bird Observatory to give it its full name - is a globally significant bellwether of the world eco-system.

Its detailed notes on the comings-and-goings of both migratory and resident species, begun in the 1940s, have helped record climate change.

Crucially, say its managers, this data has survived the fire, which broke out on Sunday morning.

So have its staff, husband-and-wife team of warden David and administrator Susannah Parnaby, and their two children, Grace and Freyja.

Their home, however, has not. It, along with the rest of complex, was yesterday nothing more than a smouldering pile of rubble.

This could have a devastating effect on an island economy that is every bit as fragile as its environment. Because the Obs is the Fair Isle’s biggest tourist attraction and main supplier of accommodation.

“This season is a write-off, “ explained Mike Wood, the Obs’ treasurer. “ So, realistically, is next. So we are looking at re-opening in April 2021 at the earliest.”

The current Obs , built in 2010, can host 36 visitors. That is about half the island’s resident population. Last year it housed some 550 individuals for a total of 3300 bed nights.

Fair Isle has some B&B’s but the Obs accounts for almost the island’s entire accommodation offering. It buys its food from the island’s only shop and its visitors help sustain lifeline flights and ferry services. Obs tourists offer a rare chance for local artisans - not least its Fair Isle knitters - to sell some of their world-famous products.

Roy Dennis was assistant warden and then warden at the Obs in the 1960s. Now he is honorary president of its board. He said: “This is a really special place and this fire has been tragic.

“We will rebuild and we will re-open but in the meantime there are going to be a lot fewer people on the planes and ferries coming to Fair Isle. It is very worrying.”

The goods news is that the facility is insured and that the independent trust which runs it is well-funded. Mr Wood stressed insurance also covered loss of income.

That means important work monitoring birds can continue. Mr Wood said the Parnabys had found alternative accommodation.

Mr Wood, Mr Dennis and other directors held an emergency tele-conference on Monday. They issued a formal statement saying their “ priority” was help the Parnaby’s with “a medium-term aim to continue with as much ornithological census and research work as is feasible in the circumstances”.

They added: “We are all still in a state of shock but are committed to rebuilding and continuing the important work of the Bird Observatory.”

Some irreplaceable things are lost, directors said. These include original artwork, and hand-written diaries from George Waterson, the pioneering Scottish ornithologist who became so passionate about Fair Isle that he bought the island (which he later passed on to the National Trust). The Obs is his legacy.

Directors, however, stressed they were not looking for immediate help. They said: “We have been overwhelmed with the outpouring of support from across the globe - from Shetland, the birding community and beyond - with many folk asking for details of how they can donate.

“We have comprehensive insurance, so at least at this time, we are not launching a major fund-raising campaign.

“There will inevitably be elements where the full cost of the disaster will not be fully covered by insurance, and once the situation becomes clearer we may launch future appeals for help to replace specific items.”

Directors did not speculate on the cause of the blaze, which was reported at 11:20am. Some reports suggested the blaze may have begun on the roof.

Directors gave their “sincere” thanks to both local retained firefighters and others brought across from Shetland by both boat, including an RNLI lifeboat, and aircraft. Small islands have part-time personnel who are trained to tackle fires but no access to the heavy equipment needed to fight major fires.

They added: “We are indebted to the Fair Isle Community for their continued support of the Obs and particularly for taking care of David, Susannah, Grace and Freyja at this time of need.”