Jebb's wife, Cynthia (1898-1990), Lady Gladwyn, was the daughter of Sir Saxton Noble and the great-grand daughter of Isambard Kingdom Brunel.
Jebb's wife, Cynthia (1898-1990), Lady Gladwyn, was a noted diarist of their times in Paris and a hostess of Liberal and London politics. She was the great-grand daughter of Isambard Kingdom Brunel.