Born Elizabeth Harman and a daughter of eye specialist Nathaniel Bishop Harman, she was educated at the Francis Holland School, and later took her Master's degree at Lady Margaret Hall, Oxford. "Able, articulate and beautiful", in the words of The New York Times, she was "the Zuleika Dobson of her day, with undergraduates and even dons tumbling over one another to fall in love with her". On 3 November 1931, she married Francis Pakenham, 7th Earl of Longford, who died in August 2001. Her obituary by the BBC said the marriage was "famously harmonious." The New York Times, in its review of The Pebbled Shore, called Lady Longford "easily the best writer in what is predominantly a literary family".