From The West Wiltshire District Guide 1978:
The Shearwater lake was formed in 1791, near Crockerton, and is part of the Longleat Estate. It was one of the last improvements made by the first Marquis of Bath who died in 1797. It was designed by Francis Duke of Bridgwater of canal celebrity and an intimate friend of Thomas Lord, Viscount Weymouth and the first Marquis of Bath. The area covered is around 38 acres or thereabouts.
The lake has been frozen over many times during severe winters. In 1879 safe skating was enjoyed there; records state that over 1,000 persons enjoyed the sport whilst it lasted. The roasting of an ox and sheep has taken place many times on the ice when conditions have allowed. The lake is a popular attraction set amid woods to the north and the south and is particularly pleasant on summer evenings.