Joyce became a vegetarian in 1971 after reading Mahatma Gandhi's autobiography. She became a vegan four years later and has published a vegan cookery book entitled "Healthy Eating for the New Age".

She has worked for Compassion in World Farming since 1985 and became its Director in 1991.

Joyce has written reports on BST, veal farming and modern farm animal breeding technologies. She has written chapters on the genetic engineering of farm animals for two books, including "The Meat Business", published this year by Earthscan. An article on BSE, which she wrote for an American magazine, was named one of the top 25 censored stories of 1994.