Bill Steen (m.1954) qualified as a jet fighter pilot during his national service in 1952-54. He came up to Christs in 1954 and graduated in Natural Science and Chemical Engineering in 1958; whilst up at Christ's he was one of the founders of the Cambridge University Tiddlywinks Club who played Prince Philip's Champions, the Goons, in 1958. He worked in industry designing the worlds first continuous brewing plant with the APV Co. Ltd in Crawley until 1962. He married Margaret in 1960 and in 1963 they went to India where he lectured in Industrial Chemistry at a rural college, Bankura Christian College, W.Bengal and whilst there he developed an interest in fish farming. In 1963 their son, Preston (m.1983), was born  in Calcutta. On returning to UK in 1965 their daughter, Melanie, was born in Cambridge. 

William joined Imperial College as a process metallurgist, lecturing during a time of rapid technological change involving computers and lasers. He wrote a PhD on laser chemical vapour deposition by building his own laser, which in 1968 represented the first university based research group in laser material processing in the world. In 1971 he was part of a United Nations study group to propose multi national industries for the East African Community. In 1977 he was awarded a grant by BOC for one of the first commercial 2kW CO2 lasers (the first went to Tokyo University). There followed some 20 years of intense research with considerable travel and numerous publications, leading to  the largest university based laser material processing group in the country, similar to that at the Welding Institute Cambridge.

In 1988 he was offered the James Bibby Chair of Manufacturing Engineering at Liverpool University, with enhanced laser facilities. The research activity moved to Liverpool with a group of about 30 scientists working on cutting, welding, cladding, weld build, cleaning, bending, marking and anything else that they thought the laser could do. In 1995 he was one of the founder members of the Association of Industrial Laser Users (AILU) and its 1st President.  In 1997 he was the first European to be awarded the Arthur Schawlow Award by the Laser Institute of America. He has a laboratory named after him at the University of Vigo, Spain, and received a medal from Palacky University, Olomouc, Czech Republic for his pioneer work on lasers. There was a tribute session to his lifetime achievements at the International Congress on the Applications of Lasers and Electro- Optics (ICALEO) in 2008. The 4th edition of his book on Laser Material Processing was published in 2010. In 2016 he had the singular honour of being elected an Honorary Fellow of the Institution of Mechanical Engineers in recognition of his pioneering activity in starting a new area of engineering with lasers and in 2020 the Laser Institute of America (LIA) initiated the “William M. Steen Award”  as an annual award for significant developments in laser material processing.

On his retirement in 1998 he moved to the Cambridge area. In 2000 Dr. Alan Munro, as Master, kindly invited him to be the editor of the College Magazine on Richard Barlow Poole's retirement from the post. This he did from 2001 to 2006 with much pleasure. Currently he serves the College by cataloguing the picture collection.

Many of his ex-students and their ex-students now either run their own business, teach, or make money from laser material processing. Seeing this happen is one of the greatest pleasures an academic can have.