Baron Lucas is a title in the Peerage of England. In 1663, it was granted to Mary Grey, who married the eleventh Earl of Kent. Her successor was the twelfth Earl of Kent, and was later created Duke of Kent and Marquess Grey. During the Duke's lifetime, his son Anthony, Earl of Harold was summoned to Parliament as Lord Lucas of Crudwell through a writ of acceleration. Earl of Harold predeceased his father, however, so he could not inherit any titles. At the Duke's death, the dukedom became extinct, but by special remainder the marquessate of Grey passed to his daughter Jemima, who also inherited the barony.
Thereafter, the barony was held by the second Earl de Grey and then the seveth Earl Cowper. The Scottish title of Lord Dingwall, which had been attained, was restored to the seventh Earl Cowper. At the Earl's death, the barony of Lucas and the lordship of Crudwell was inherited by Auberon Thomas Herbert, and the titles have remained united since.