Prof John Davidson will celebrate his 90th birthday on 7 February 2016 and the occasion was marked by a gathering in the Tea Room on 2 February.
Head of Department, Prof John Dennis, said a few words about Prof Davidson's long career in Chemical Engineering and his equally long association with this department.
John Davidson joined the Department of Chemical Engineering, Cambridge University in 1952 as a University Demonstrator. He became Professor of Chemical Engineering (Shell Professor from 1978) and Head of Department from 1975 through to his retirement in 1993.
In 1999 he was awarded a Royal Medal in recognition of his distinguished work over many years in Chemical Engineering, including fluid flow, process dynamics, gas absorption and fluidization technology. He has been a Fellow of the Royal Society since 1974.
John Dennis praised John Davidson's ability to reduce any problem to four handwritten sides of A4 and cited an example where his clarity of thought beat a computer program that took three days to write.
John Dennis presented John Davidson with a card and present and John Davidson replied with a brief speech remembering the early days of the department with recollections of Professors Fox and Danckwerts.
John Davidson then cut the cake which was quickly eaten by his many friends and colleagues.