[6][7] After graduating from Cambridge, Collar joining the Aerodynamics Department at the National Physical Laboratory in Teddington, where he worked on propellers, airship dynamics, wind-tunnel design, and especially on flutter and matrix analysis.
Collar worked on these challenges in collaboration with Robert Alexander Frazer and William Jolly Duncan.
During World War II, Collar led an aeroelasticity research team at the Royal Aircraft Establishment in Farnborough, where according to Bishop the "main work of Collar's section was to try to alleviate or prevent the adverse effects of elastic distortion in aircraft – those of loss of control, vibration and flutter.
"[6][7] After the war Collar "visited German research establishments and scientists", according to Bishop, to exchange information about new advances in aeronautics.
In 1946, Collar was appointed to the newly established Sir George White Chair of Aeronautical Engineering at Bristol University.
[6] Collar's book Elementary Matrices and Some Applications to Dynamics and Differential Equations, written with Robert Alexander Frazer and William Jolly Duncan and published in 1938, quickly became a standard text in the field and is described as a "classic" in The Schur Complement and Its Applications by Fuzhen Zhang.
Bishop calls it a "masterpiece", noting its many reprintings over several decades in Britain and the United States and its translations into other languages.
He also describes Collar as "a very entertaining raconteur....In general conversation...there was rarely a dull moment and he had a great fund of quotations, particularly from W. S.
Bishop notes that Collar's outside interests "were both substantial and numerous", including "games and puzzles, reading, poetry, music and....watching tennis, football (of both varieties) and cricket.