There is another longstone in the parish of St Cleer, about two miles north of Liskeard, which bears an inscription to Doniert (Dungerth), a traditional king of Cornwall, who was drowned in 872. In fact these “menhirs,” supposed to be sepulchral monuments, are to be found scattered all over the county.
The Folk-Lore Journal Volume 5 1887 (Cornish Folklore)
These two fragments, one of which is known as King Doniert’s Stone, are the only surviving examples of 9th-century stone crosses in Cornwall. The inscription on King Doniert’s Stone, bearing the name of a Cornish king, is the only such cross to feature a character known also from documentary sources.
The early missionaries are thought to have set up wooden crosses to proclaim the victory of Christ in the places where they preached: in time these sites became sanctified, and stone crosses were erected in place of the older wooden ones. King Doniert’s Stone may be the base of one such cross and the taller broken shaft alongside it is probably another.
King Doniert’s Stone stands about 4 feet 6 inches (1.37 metres) high, and is decorated on three of its faces with interlaced ornament of a style common throughout Britain. The upper end of the stone has a deep mortice in the top to take an upper shaft or cross head. The east face bears a weathered inscription which reads Doniert rogavit pro anima (‘Doniert has asked [for this to be made] for his soul[’s sake’]). The clue to Doniert’s identity lies in a passage in the early Welsh chronicle known as the Annales Cambriae, which names a king of Dumnonia called Dumgarth (or Dwingarth). He is recorded as having drowned in the sea in about AD 875.
The southern cross-shaft fragment is taller, about 7 ft (2.1m) high, and one face has a panel of interlaced decoration. Excavations have revealed an underground rock-cut passage that starts to the south-east of the crosses and terminates in a cross-shaped chamber beneath the two stones. The relationship between the underground chamber and the crosses has yet to be explained.
Both stones, as we see them nowadays, are only small fragments of original stone crosses, and there can be no doubt that when first set up, these were impressive monuments. Assuming that the Doniert Stone does indeed commemorate a Cornish King, one can only speculate on its purpose, standing as it does beside a track only 12 miles from Hingston Down where in 838 the Anglo-Saxon King Edgar had defeated a combined force of Danes and Cornish, thus decisively bringing Cornwall under English control. Similarly designed cross-shafts can be seen at nearby St Neot Church and St Just in Penwith in Cornwall, as well as at Copplestone near Crediton and Exeter (in the Royal Albert Memorial Museum) in Devon. In South Wales, ‘composite’ and interlace-decorated crosses like these are found at Nevern and Carew, although whether there is any relationship between the two groups is uncertain.
In the seventeenth century local miners prospecting near the crosses broke into an underground chamber beneath the stones. Despite various theories suggesting that the chambers might represent a chapel or vault associated with the stones it seems far more likely that they relate to mining activities in the area.
The field adjacent to the one in which these two crosses originally stood is identified as “Two Cross Downs” on the 1840 Tithe Map, probably in reference to these two crosses. The name also gives a clue to their original setting. Though now within a small enclosure surrounded by farmland, the stones would once have stood on open downland
Cornwall’s Archaelogical Heritage