Legs that are red below the knees and hocks are considered faulty in colour, although they do not disqualify a horse from registry.[1] The occasional red legs that appear in the breed are thought to come from chestnut Thoroughbred stallions that were crossed into Cleveland Bay and Yorkshire Coach Horse bloodlines at some points in the history of both breeds.[3] The uniformity in colour is encouraged as it makes creating matching driving teams and pairs very easy.[4] When the breed was first developed, the horses almost always had a countershaded dorsal stripe, but these disappeared with the outcrossings of the 18th century.[5]