I have been thinking for some years about the decoration on the Queen Mary harp, ever since medieval academics at the 2008 Leeds International Medieval Congress suggested that while the pillar is clearly 15th century West Highland, the box and neck look earlier.
Today I was down at the cathedral here in St Andrews and I took some photos of 12th century designs on the Cathedral stonework, to compare with the designs on the harp.
Left & right: replica Queen Mary harp soundbox designs; Centre: Outside of chancel end wall at St Andrews cathedral. (I understand this is a consecration cross. There is another, damaged, on the end wall of the south transept).
Above: arcade inside the South transept at St Andrews cathedral. Below: replica Queen Mary harp neck design.