The Cotswolds became very prosperous in the 14th and 15th centuries and Campden, in particular, thrived. The wool from the long-backed Cotswold Lion sheep was prized across Europe. William Grevel, the son of a local man, became one of Campden's (and, by repute, one of England's) most successful wool merchants. In about 1380 he built a new house in the High Street (Grevel House) that still stands today. The Woolstaplers Hall on the other side of the High Street was built in the 14th century by Robert Calf and illustrates how Campden had become an important collecting point for fleece, later sold to Flemish and Italian clothiers.