Lewis graduated from London University in 1959 and qualified as a Chartered Surveyor in 1961. Three years later he formed his own firm of Chartered Surveyors in 1964. He has held a number of public company positions in the UK and is Chairman of various privately controlled investment companies.
He is a former Chairman of the Jewish Blind Society (19791990); Jewish Care (19911992), of which he was Senior Vice President (19932016); President of the European Council of Jewish Communities (19921999). He was a founder Governor of the Harris City Technology College, Croydon (19902009). He is a Governor of the Oxford Centre for Hebrew and Jewish Studies, where he was Chairman of its Library (19742011). He is Co-founder and Co-chair of the Commission for Looted Art in Europe and a Trustee of the Wiener Library and the Birmingham Museums Trust and Leuka.