In civilian life Roberts was employed by water engineering consultant John Taylor & Sons and remained with them and their successor bodies for the rest of his career.
He became founder chairman of the successor Acer Consultants in 1987, holding the post for five years, during which the group's turnover quadrupled and employee numbers trebled.
[4] Roberts was sent to Kuwait in 1952 to design that country's first water-distribution system, an assignment that began a lifelong association with the Middle East.
[4] Roberts became John Taylor's senior partner in 1984 and was elected president of the Institution of Civil Engineers for the 1986–87 session.
[11][12] He was also a member of the Natural Environment Research Council from August 1987 to July 1993 and was made a Commander of the Order of the British Empire in 1987.
[13] Roberts became co-chairman, and later chairman, of Acer Consultants, which was formed in 1987 following the merger of John Taylor & Sons with Freeman Fox & Partners.
[14] During his career Roberts also served as chairman of the British Geological Survey, of the Football Stadia Advisory Design Council, the Second Severn Crossing Technical Adjudication Panel and as visiting professor at Loughborough University.
[4] He remained involved with his alma mater, becoming president of the Merchant Taylors' School Old Boys' Association in 1998 and an honorary fellow of Sidney Sussex College in 1994.