Margaret Cavendish Bentinck, Duchess of Portland was the richest woman in Great Britain of her time, styled Lady Margaret Harley before 1734, Duchess of Portland from 1734 to her husband's death in 1761, and Dowager Duchess of Portland from 1761 until her own death in 1785.

The Portland Vase is a Roman cameo glass vase, which is dated to between AD 1 and AD 25, though low BC dates have some scholarly support. It is the best known piece of Roman cameo glass and has served as an inspiration to many glass and porcelain makers from about the beginning of the 18th century onwards. It is first recorded in Rome in 1600–1601, and since 1810 has been in the British Museum in London, although until 1945 it was on loan from the Dukes of Portland. It was bought by the museum in 1945 and is normally on display in Room 70.