What caused the disappearance of the Flannan Isle lighthouse keepers?

Were the lighthouse keepers on Flannan Island swept away? Or did something darker take place that night? 

2019 film The Vanishing is based on the true story of the mysterious disappearance of three lighthouse keepers. Set in the Flannan Isles in the Outer Hebrides of Scotland, it tells the tale of Thomas Marshall, James Ducat and Donald MacArthur, who were all discovered missing in December 1900.

The mystery of Flannan Isle Lighthouse was first discovered when the steamer Anchtor made note in its log that the light was not working in bad weather conditions. This was further confirmed when the relief vessel Hesperus arrived at the island, and found the island in a mysterious state of disarray.

There was no welcome from the lighthouse keepers, no flag on the flagstaff and no provision boxes left for them as was customary.

The relief keeper Joseph Moore was sent to investigate further and found the main door and gate to the compound closed, the beds unmade and the clock stopped. They also found a set of oilskins, suggesting one of the keepers to have left without them – unusual and worrying considering the poor weather conditions that had been recorded in the log.

The island was scoured for clues, or any sign of the keepers, but nothing was found. The west landing had received considerable damage, with turf ripped up and a box of supplies destroyed, with its contents strewn about. The keepers log proved that this damage had occurred before the disappearance.

The log leading up to the men’s disappearance included some strange entries, with descriptions of an awful storm, high winds, and low spirits amongst the keepers. There were however no reports of storms in the area in the days leading up to the disappearance, meaning that the poor weather conditions recorded in the log were either made up, or localised.

To this day no one knows what took place in the lighthouse that night, but many theories have developed over the years.

The more far-fetched of these theories suggest they had been carried away by a giant seabird, had been abducted by spies or had simply escaped to start new lives. The perhaps more plausible theories suggest that the keepers had been swept away when trying to secure a box in a crevice above sea level. Other theories suggest the psychology of the lighthouse keepers played a part. MacArthur had a reputation for brawling and was known to be violent. It is suggested by some that a fight broke out on the cliff edge, causing the men to fall to their deaths.

The designer of Flannan Isle Lighthouse, David Alan Stevenson also designed the Tarbat Ness Light, which is on display at the National Maritime Museum. It was designed and built because of the loss of sixteen vessels in the Moray Firth storm in 1826 on Tarbat Ness.

We will never truly know what happened to the lighthouse keepers on Flannan Island, but the enduring design of Stevenson’s work lives on.

The Vanishing is in cinemas from 29 March and available on digital platforms from 1 April. Royal Museums Greenwich Members had a chance to see the film before the general release at a special preview screening at the National Maritime Museum.