Eventually only one of William and Charlotte's eleven children remained at the Mill, William II. He, too, worked on the development of the business.

He enhanced the colours used at the Mill, introducing Fustic from the West Indies, Red Madder, Barwood, Yellowood and Camwood from Angola. He also used Logwood from Honduras, which produced a rich blue-black colour that turned green under different light conditions.

The dyes would be shipped to Liverpool, delivered by water to Kendal and then collected by William by horse and cart in a journey of over 100 miles. This would see him setting out on a Monday morning and returning on the following Saturday evening.