Born in Barnet, Hertfordshire, to chartered accountant Dudley Oxenford and his wife Marie (née du Grivel), a writer of historical fiction,[3] Oxenford first appeared on stage at the age of thirteen and trained at the Embassy School of Acting in Swiss Cottage, North London. She was briefly employed by a bank before working in censorship during World War II while performing in revues in her spare time. At the end of the war she toured with ENSA before returning to revues in London.