Lehman was born in Germany on 24 January 1925 and emigrated to England in 1931. He studied
mathematics as an undergraduate at
Imperial College London where he was involved in the design of the
Imperial College Computing Engine's Digital Computer Arithmetic Unit. He spent a year at
Ferranti in London before working at
Israel's Ministry of Defense from 1957 to 1964. From 1964 to 1972, he worked at
IBM's research division in
Yorktown Heights, NY where he studied program evolution with
Les Belady. The study of IBM's programming process gave the foundations for
Lehman's laws of software evolution. In 1972, he returned to Imperial College where he was Head of Section and later Head of Department (1979–1984). Lehman remained at Imperial for some thirty years until 2002 when he moved to the School of Computing Science at
Middlesex University. After retiring from Middlesex he moved to Jerusalem, Israel, where he died on 29 December 2010. ==Awards and honours==