Shields was born in London and served as a major in the Royal Artillery in World War II, during which time he was awarded the Military Cross.
In 1949 he unsuccessfully stood as the Conservative Party parliamentary candidate for St Pancras North.
Shields later became an adviser in merger broking, especially in the role of director of Chesham Amalgamations and Investments (1964–1984).
The commission, under his chairmanship, was converted from a holding body to a disposal agency, selling off billions of pounds of assets.
At the same time Shields also served on the board of London Transport (1986–1993), six months doing so as interim Chairman (1988–89) after the Fennell report into the King's Cross fire, and afterwards as deputy chairman.