The appointment of William Wynford as master mason in 1365 marked another period of activity. He was one of the foremost architects of his time and, apart from Wells, was engaged in work for the king at Windsor and at New College, Oxford University and Winchester Cathedral. Under Bishop John Harewell, he built the south-west tower of the West Front and designed the north west, which was built to match in the early 15th century. Inside the building he filled in the early English lancet windows with delicate tracery.