[1] McDonagh was born in Harpurhey, Manchester, England on St. Patrick's Day 17 March 1934, the eldest of four children in a family of Irish origins.
[1] She worked as a model in London and Paris in the late 1950s, on television and in print,[3] and in the fashion houses of Jacques Helm and Maggy Rouff.
[1] Following her marriage to David Main in 1960, and the birth of her first two children, McDonagh opened boutiques in Horwich and Worsley, Lancashire.
Styles were old-fashioned, and materials were difficult to obtain due to poor domestic production and high import taxes.
She went on to open a factory, the product of which was known as the Re-Establishment range,[1] and to sell her clothes across Canada and the United States, including in Bloomingdale's, Bonwit Teller and Henri Bendel in New York.
[3] In England, McDonagh designed costumes for Diana Rigg as Emma Peel in The Avengers for whom she created leatherwear and python-buckled coats which she called "a very sophisticated, slightly fanciful take on what was happening in the swinging London club scene of the time".
[7] Near the end of her life, she spoke of a simple dress worn by the central character in the 1927 film Metropolis which had inspired her.