I believe that Danny may be correct. Plinth is chalk stone used as a band round a building almost like a damp course, clunch is used for complete buildings.
Paint Colours | Clunch | Farrow & Ballhttp://www.farrow-ball.com/clunch/paint-colours/farrow-ball/fcp-product/102009Clunch is aptly named after the chalk stone used in building blocks because it has a very dependable feel to it