The museum holds a wonderful collection of carved stones, inscribed slates and other artefacts from the island of Inchmarnock (lying off the west coast of Bute.)
In the early 1970s, the Middleton family, under the guidance of Dorothy Marshall, undertook an amateur excavation of the site of an early Christian chapel which was in the stackyard of their farm. The Royal Commission came over and did a full set of drawings of the site.
When the island was purchased by Lord Robert Smith, he commissioned a full excavation lasting several seasons. Jessica Middleton joined this excavation, keeping the family link with the site. She found the bottom half of the stone now known as the Hostage Stone.
The Inchmarnock Cross.
This was found in two parts built into the stackyard wall, the first part in the late 19th century and it became part of the museum collection in 1913. Over 60 years later the top half was found in the same wall and was reunited with its bottom half in the museum in 1986. One side of the stone is carved with a Latin cross. The other side has carved saltires and what looks like two doves beak to beak.
A very important part of the finds from Inchmarnock were a collection of inscribed slates and stones. This collection was awarded jointly to Bute Museum and the National Museum of Scotland. The slates help to tell the story of the monastery on Inchmarnock from its early beginnings to more recent times. The assemblage includes boards for games as hnefetafl and merles (games of strategy being an important part of the education of young boys).
Slates were used like scrap paper is nowadays, to draw out ideas before committing them to expensive vellum, so there are trial letters, designs and small scraps of text. Two languages are used, Latin and Gaelic. Some of the inscriptions would be made by monks but others seem to be the work of their pupils The most important of these slates are on permanent display in Bute Museum, although there are often a few on loan to other museums
This stone is thought to be the work of a young novice at the monastery. It depicts a scene where a hairy, scary Viking is leading away a monk carrying a reliquary. Other figures in chain mail and cross-hatched leggings are depicted. The monk is being led to a Viking ship, oars ready to row him away. This little sketch is of such importance that it is frequently requested on loan by other museums and for most of 2014 it will be in Denmark at the Viking Ship Museum in Roskilde. While on loan, a replica can be seen with the other slates in the Bute museum.