It was one of the most powerful storms to hit Scotland in recorded history, bringing 120mph winds in its wake along with blizzards, high seas, thunder and lightning.

And now scientists say that the extreme weather event which hit in the early 1990s was so strong it killed off much of a Scottish island’s entire growth of heather for the year.

The Braer Storm which struck in 1993 was the product of a the most intense cyclone ever recorded over the northern Atlantic, a force of nature which delivered hurricane-force winds to parts of northern Scotland and left its mark on the landscape.

It was also responsible for the destruction of the tanker MV Braer – which gave the storm its name – which was already floundering on rocks on the Shetland Isles.

The oil which spilled from the wreck has been blamed for wreaking Scotland’s worst ever environmental disaster when 85,000 tonnes of oil leaked into the sea.

However, the storm also had another affect on life in the area, which has not been understood until now.

A project to study St Kilda’s Soay sheep – the rare ruminants left behind on the island when it was abandoned in the 1930s – has found that the amount of heather on the island declined incredibly after the 1993 storm.

It is thought that the severe winds whipped up by the storm carried salt from the sea on to the land, poisoning the heather and killing off much of that year’s growth.

Professor Michael Crawley of Imperial College London has been leading the research effort on the island, which has been collecting data on the quantity of heather for the last 30 years.

Professor Crawley, from the Faculty of Life Sciences, said: “A plant of particular interest is heather, and our long-term data clearly show that since about 1998 the plants have been fluctuating but gradually increasing despite the grazing.

“What we noticed was that from 1993, when this part of the study began, there was a steep rise in the abundance of taller heather.

“It is most likely, although of course we can’t know for sure, is that this followed severe heather die-back at some stage before August 1993. “The most likely cause is inundation by salt spray during a winter storm.”

The 1993 Braer Storm developed as a weak frontal wave on January 8, 1993, before moving rapidly northeast, bringing severe blizzards across much of Scotland.

It also had a cataclysmic effect for the oil tanker MV Braer, which was had been stranded on rocks at Quendale Bay, just west of Sumburgh Head the week before.

The ship, which was carrying crude oil from Norway and was bound for Canada lost power and drifted on to the rocks, and efforts to tow it off had got under way just before the storm arrived.

Already leaking oil, the tanker dumped its entire load into the waters when it was broken up by the storm, leading to the deaths of around 1,500 seabirds, according to the WWF.

It also led to a ban on seafood from the area, including farmed salmon, but this was soon rescinded.

The strength of the Braer Storm is believed to have helped dissipate the oil spill as the rough seas churned the crude oil – which was of a biodegradable form – into nothingness.

The oil spill is now regraded as a “close shave”, whose ecological damage could was been exponentially worse had it occurred in calmer seas or closer to the mainland.

However, the size of the storm has been revealed by the Imperial College study on St Kilda, which lies 320 miles to the the southwest of Shetland, on the other side of the British Isles.

The rural island is one of the the remotest places in Scotland and is about 40 miles (64km) west of North Uist, the nearest inhabited place to the archipelago in the Outer Hebrides.

St Kilda attracts around 5,000 visitors a year, with Ministry of Defence (MoD) staff and conservationists also making a temporary home on the island. The last permanent resident was evacuated 90 years ago as living conditions became too tough.

With the MoD base being rebuilt, up to 70 people were living on the island last summer although the temporary population usually sits at around 30 to 40 people.

The last islanders left St Kilda in 1930 and people only now live on the main island of Hirta on a temporary basis to work at the military site, or on wildlife conservation or research projects.

Its population of hardy Soay sheep is thought to have descended from animals which once lived on the island and have now gone feral, and is unique to St Kilda and its neighbour islands.