at crufts on the inter regional obedience comp, there was a smooth collie working A. it was down as a smooth & didnt have a "rough" coat, BUT it did have a coat,lots of feathering etc. do smooths sometimes through coated dogs???
Until a few years ago, the Kennel Club used to allow Roughs and Smooths to be mated together. I believe that occasionally you now get a 'longer coated smooth' in Smooth litters! Just goes to show the need for truly knowing your dogs pedigree a LONG way back before breeding!