The decoration on the Otway harp is clearly divided into two different types. The neck and pillar are decorated all over with carved and blackened lines, and the panels between the lines are filled in with an alternating chequerboard arrangement of red and blue paint. Much of this original paint survives and demonstrates a suprisingly vivid original colour scheme.
The soundbox by contrast is quite plain, with subtle decoration - the hexafoil soundhole fretwork, and the double arcading lightly incised down each edge.
Armstrong (1904) gives good overview and detail line drawings of the Otway's decorative scheme, but he does not show the paint colour scheme.
The hexafoil soundholes and the arcaded border of the soundbox suggest that the soundbox at least might have been made by Cormac O’Kelly in the early 18th century; they match motifs and decorations seen on the Downhill harp and the watercolour of the Magenis harp, which are both also signed by O’Kelly. Then there is the question of whether the incised and painted motifs on the neck and pillar are also by O’Kelly, in a different style, perhaps imitating and older style; or whether this decoration is genuinely older.