During World War II, Edward Middleditch served in the army in France and Germany and later in Burma and West Africa. He was awarded the Military Cross in 1945. In 1948 he took classes at the Regent Street Polytechnic in London and the following year he joined the Royal College of Art on an ex-serviceman's grant, where teachers included Ruskin Spear, John Minton and Carel Spear until 1952. He began teaching at Chelsea School of Art in 1954, moving on to Regent Street Polytechnic, Cambridge School of Art, St Martin's School of Art and finally to Norwich School of Art, where he was appointed Head of the Department of Fine Art. He remained there until his retirement in 1984. In the same year he was elected Keeper of the Royal Academy in charge of the Schools; he was also a selector for the Summer Exhibition in 1985. He retired as Keeper in 1986.
While at the Royal College of Art, Middleditch met fellow students Derrick Greaves, Jack Smith and John Bratby. All four artists were given regular exhibitions in Helen Lessore's Beaux-Arts Gallery in London from 1951 to 1965 and were conferred the title 'the Beaux-Arts Quartet'. They later became known as the Kitchen Sink School after critic David Sylvester coined the term in the December 1954 in response to their unique brand of realism inspired by everyday life in post-war Britain, and the four artists were selected to represent Britain in the 1956 Venice Biennale.