A Scottish island that issues its own postage stamps is being offered for sale for £2.5 million.

Tanera Mor, the largest and only inhabited island in the Summer Isles archipelago, is being sold by the Wilder family, who bought it in 1996. Lying off Wester Ross, the 800-acre isle was the setting for Frank Fraser Darling's 1943 book Island Farm.

Bill and Jean Wilder bought the island after selling their Wiltshire dairy farm. The island is managed by their daughter, Lizzie, and her husband, Richard Williams.

The family held discussions with the local Coigach community, which includes the mainland village of Achiltibuie, to establish whether locals would be interested in buying the island before it was put on the open market.

Yet the Coigach Community Development Company has decided against leading a community buy-out because of its existing commitments, which include two micro-renewable energy projects and the recently completed purchase of the former Achiltibuie Smokehouse.

Lizzie Williams said: "After many happy years of calling Tanera home, it is time for someone else to have the privilege of looking after this amazing place. We greatly appreciate the effort made by the local Coigach community to consider the opportunity of taking on Tanera and we fully understand their reasons for deciding not to. We hope that whoever owns the island in the future will enjoy the same warm and co-operative relationship with the community that we have for the past 17 years."

As well as being home to otters and seals, the island's natural harbour formerly provided a safe stopover on northward sea journeys before the nearby mainland port of Ullapool was established.

Mr and Mrs Williams live on the island all year round, but the population grows in summer with seasonal staff running self-catering holiday lets, the post office, cafe and sailing school. Around 5000 people visit the island annually, many on tourist boats from Ullapool and Achiltibuie.

Over the past 15 years, the family has also undertaken a woodland regeneration project by planting more than 164,000 native trees.

In a rare deal struck in 1970, the Summer Isles Post Office, which operates from a former boathouse on Tanera Mor, issues its own postage stamps, with this year's edition to be released on Thursday.

The island is being marketed by the Inverness office of property consultants CKD Galbraith.

John Bound, of CKD Galbraith, said: "The chance to own your own Scottish island is extremely rare and with Tanera Mor's thriving tourist enterprise coupled with being a truly spectacular place to live, we expect to receive a lot of interest as it goes on the open market.

"With ongoing support and commitment from the local Coigach community, Tanera Mor offers a truly fantastic prospect for interested parties who will very much have the island's heritage and sustainability at heart as well as a fantastic lifestyle."

The 1973 film The Wicker Man is set on the fictional island of Summerisle, which is thought to have been based on Tanera Mor.