She married Edward Herbert, Viscount Clive on 9 February 1818.[2] He succeeded to the Powis earldom in 1839, at which point Lucy became Countess of Powis. The couple had seven children:
The Earl of Powis died on 17 January 1848 at his home in Powis Castle after being accidentally shot during a pheasant hunt by one of his sons, the Hon. Robert Charles Herbert, ten days earlier.[3] He was buried at St Mary's Parish Church, Welshpool. The countess herself died in 1875 at Walcot, Shropshire, where the family had another home.
A portrait of the countess, at around the time of her marriage, was painted by Frederick Richard Say and is held at Powis Castle.[4]