A 117m long incline, originally linking Floors 3 and 0 at Diffwys quarry. Only a 75m stretch of the incline between Floor 0 and 2 remained in use by the first edition Ordnance Survey of 1889 and this was out of use by c. 1900 and the second edition Ordnance Survey.

The stone built incline plane survives up to Floor 3, where the remains of a drum-house survive. Access for the quarrymen in the form of a path and steps are situated on the west side of the incline between floors 0 and 2. An additional retaining wall and buttress are further features associated with this incline located near Floor O around an adit entrance.

Louise Barker, RCAHMW, October 2015