Sells Ltd, an advertising agency, was opened in 1869 in London.^[1] By 1900, it was the largest agency in the world with offices in London, Paris, Edinburgh and Montreal. In the 1950s, it made advertising history when it appointed the first woman to be a managing director in the business. Olive Hirst had joined Sells in 1931 as a typist and then worked across a number of departments. In January 1950, she was the first women to be appointed to the Board and in 1954 she took over the managing directors role.^[2]

The agency won the Layton Trophy in 1959.^[2]

The agency was merged with another in the 1960s.^[1]