People on St Kilda developed an unusual way to communicate with the outside world from their remote island home – by launching post into the sea in small waterproof vessels.

Living on an archipelago 40 miles west of the Outer Hebrides, the only way islanders could make contact with other communities was by asking boats that called there in the summer months to carry their post and pass it on.

Journalist John Sands came up with the idea of creating mailboats in the 1870s when he became stranded there.

A mailboat that he launched in 1877 was found in Birsay in Orkney nine days later, and a boat was sent to rescue Sands and nine shipwrecked Austrian sailors who were also marooned on St Kilda.

Mailboats helped bring aid a few years later in September 1885 when the islanders were facing starvation after their food stores were left ruined following a severe storm.

Alexander Gillies Ferguson, a 14-year-old schoolboy, had heard of the mailboats developed by Sands and launched five vessels which contained messages asking for help.

One of the boats soon arrived in Gallan Head, Lewis, and help was sent to the islanders.

Over the decades, St Kildans continued to use mailboats to make contact with the outside world – and while some reached the Scottish mainland others floated as far as Iceland, Denmark and Norway.

The mailboats were made from a range of materials with the letters placed in a waterproof container which could be a tin or a bottle, and attached to something that would float such as a piece of wood or a buoy which may have been made from an inflated sheepskin bag.

The last 36 people living on the archipelago were evacuated on August 29 1930 after they wrote a letter to the secretary of state for Scotland saying that life on the island was not sustainable.

The uninhabited archipelago, home to nearly one million seabirds, has been in the care of the National Trust for Scotland (NTS) since 1957.

It is the UK’s only dual Unesco World Heritage Site – for natural and cultural heritage – and is home to the UK’s largest colony of Atlantic puffins.

Susan Bain, NTS Western Isles manager, said: “It’s an amazing place, I think everybody that goes there is just stunned by the landscape, it’s almost like a lost world.

“The islands of the St Kilda archipelago are quite jagged and come straight up out of the ocean and just the density of sea birds is fantastic and it’s also amazing for the cultural landscape with what people left behind like the empty houses.”

St Kilda comprises of five islands – Hirta (the main island), Soay, Boreray, Dun and Levenish – in the North Atlantic, 100 miles off the west coast of Scotland.

Normally NTS runs work parties on St Kilda over the summer months where people can help with conservation and research, but the islands are currently closed to visitors due to the coronavirus pandemic.

Ms Bain urged people to support NTS which is currently running its Save Our Scotland appeal to help it protect the nation’s “most loved places” as it expects to lose £28 million in income this year due to coronavirus.

She said: “It’s an amazing place but it does take a lot to keep it like that. I’m worried that we’ve lost a year of work so it would be fantastic if people could support us in our work programme for next year.”