Medievalists.net has a brief report about the discovery of a number of sculpted figures behind a tomb in the choir of Dunkeld Cathedral in Perthshire.
Less survives in Scotland than in England not only of actual medieval churches but also of their internal decoration and furnishing. Thus at Dunkeld the northwest tower and nave of the cathedral are in ruins but the choir still serves as the parish kirk.
It was in 1600 that the choir was reroofed and I would suggest that it was at that time that the freestanding tomb of Bishop Robert de Cardeny was moved and built into the wall, thereby immuring the other carvings. There is a well illustrated account of the remains of the cathedral from Wikipedia at Dunkeld Cathedral
The article has a list with links of burisls at the cathedral. These include Alexander “The Wolf of Badenoch” (d.1405) and son of King Robert II, whose tomb in the cathedral is one of the few surviving medieval Scottish royal effigies and Count Charles Edward Roehenstart (d.1854) the grandson of Bonnie Prince Charlie.
Although not one of the largest or most impressive of medieval Scottish cathedrals Dunkeld was deemed to be the third in rank after the two Archiepiscopal sees of St Andrews and Glasgow. The somewhat complicated of episcopal succession both before and after the reformation of 1560, as well as after 1689, and the restored Catholic diocese after1878 is set out, again by Wikipedia at Bishop of Dunkeld
Wikipedia has a short biography of Bishop Cardeny, the longest serving holder of the diocese of Dunkeld, at Robert de Cardeny
The description of these latest discoveries can be found at 15th century carvings discovered at Scottish cathedral