She was born in Kensington, London, the daughter of Robert Walpole, 5th Earl of Orford, and his American-born wife, Louise Melissa Corbin.

Her half-sister is Lady Anne Berry (née Walpole), the Anglo-New Zealand horticulturist who founded Rosemoor Garden, Devon.

While planning a trip to Egypt and the Middle East,[4] her father, Lord Walpole, died in Manurewa, Auckland, New Zealand, on 27 September 1931.

[citation needed] Her father's death allowed Lady Dorothy to access a trust fund left to her in 1918 by her American grandfather, Daniel Chase Corbin, of Spokane, Washington, a millionaire railroad and agricultural tycoon who mistrusted the Earl.

[6] Lady Dorothy "retreated to a quiet and private life" at the seaside Steyning Mansions Hotel at Eastern Terrace in Brighton, publishing no more books before her death in 1959.