The robbery took place in August (1963) in the summer and yet the scenes shown are clearly shot in winter/early spring due to the trees lacking leaves.
Police Officers are shown wearing white shirts. In 1963 Constables and Sergeants in all English police forces wore blue shirts. The change to white shirts came in the late 1970s.
The getaway cars at the November 1962 London Airport robbery have "A" suffix registrations, not introduced until February 1963.