An archive belonging to the family of Robert Louis Stevenson has sold for more than twice the anticipated value at auction.

The archive spanned four generations of the Stevenson family, who pioneered lighthouse design and other civic infrastructure, across 200 years.

It began from the birth of Robert Stevenson in 1772 to the death of D Alan Stevenson in 1971, and included personal artefacts belonging to Treasure Island author Robert Louis Stevenson.

The author’s grandfather, Robert Stevenson, invented intermittent flashing lights, and his descendants designed most of Scotland’s lighthouses.

The collection was tipped to sell for at least £45,000 at the Lyon & Turnbull sale of rare books, manuscripts, and maps on Wednesday.

However it sold for two-and-a-half times that estimate, fetching £115,000.

Cathy Marsden, head of books and manuscripts at Lyon & Turnbull, said: “We were absolutely delighted with the final result for the Stevenson Collection, which exceeded all our expectations.

“We are very happy to say that all the books, manuscripts and other items have found good homes.

“I am sure these lots will continue to offer the buyers a wealth of enjoyment and research opportunities.”

Alex Dove from L&T confirmed it was premium inclusive.