Background
Boscawen was the son of Hugh Boscawen of Tregothnan, Cornwall by his wife Margaret Rolle, daughter of Robert Rolle (1560–1633) of Heanton Satchville, Petrockstowe, Devon. He was baptised on 28 October 1627. His brothers were Hugh Boscawen (1625–1701), Member of Parliament, and Edward Boscawen (1628–1685), Member of Parliament, (father of Hugh Boscawen, 1st Viscount Falmouth (1680–1734)) both of whom also represented Cornish constituencies.
The Boscawens are an ancient Cornish family.
His father Hugh Boscawen (f11620) of Tregothnan was thirteenth in descent from a certain Henry de Boscawen. He derived a huge income from his copper mines at Chacewater and Gwennap where he was the principal landowner.
The Chacewater mine, now known as Wheal Busy, was located in what was known at one time as "the richest square mile on Earth". During its life it produced over 100,000 tons of copper ore, and 27,000 tons of arsenic.
