Born Elizabeth Gwynne, she was of mixed English and Irish ancestry, and came from a rather grand background, growing up in the 17th-century Sussex manor house, Wootton Manor. Her parents were Rupert Gwynne, Conservative MP for Eastbourne, and the Hon. Stella Ridley, who came from a distinguished Northumberland family. They had three other daughters.

She studied Literature and History at the Sorbonne, living with a French family for two years, which led to her love of France and of food. At the age of 19, she was given her first cookery book, The Gentle Art of Cookery by Hilda Leyel, who wrote of her love with the food of the East. If I had been given a standard Mrs Beeton instead of Mrs Leyels wonderful recipes, she said, I would probably never have learned to cook.

Gwynne had an adventurous early life, leaving home to become an actress. She left England in 1939, when she was twenty-five, and bought a boat with her married lover Charles Gibson-Cowan intending to travel around the Mediterranean. The onset of World War II interrupted this plan, and they had to flee the German occupation of France. They left Antibes for Corsica and then on to Italy where the boat was impounded; they arrived on the day Italy declared war on Britain. Eventually deported to Greece, living on the Greek island of Syros for a period, Gwynne learnt about Greek food and spent time with high bohemians such as the writer Lawrence Durrell. When the Germans invaded Greece they fled to Crete where they were rescued by the British and evacuated to Egypt, where she lived firstly in Alexandria and later in Cairo. There Gwynne started work for the Ministry of Information, split from Gibson-Cowan, and eventually took on a marriage of convenience, more or less as her aunt, Violet Gordon-Woodhouse, had done. This gave her a measure of respectability but Lieutenant-Colonel Tony David was a man whom she did not ultimately respect, and their relationship ended soon after an eight month