sentences:  It was noted for its Cornish Unit house, made from concrete which used spoil from the clay pits; in the early 1950s it was the largest producer of pre-cast concrete system houses.The division built for local authorities across the country and developed private housing estates in its local Devon and Cornwall areas – an activity which was to be substantially expanded in the years to come.After the 1960s, ECC began to regard private estate development as a suitable investment for surplus cash generated by the clay operation.