Treble lock, unique on the Glamorganshire Canal, if not in South Wales, giving a total change in level of 9.420m (30ft 11in). C.N.Johns reports that the locks were built over in 1969 by the A470 road and were left largely intact but buried; he carried out a survey just before they were covered over. 'Three Locks Cottages', adjacent, were built between 1900 and 1919, south of the original lock cottage.
B.A.Malaws, RCAHMW, 30 March 1998.