During World War II in 1940, Hassall served in an anti-aircraft gun emplacement with editor John Guest, architect Denys Lasdun, and socialite Angus Menzies [REF].
Hassall died on a train at Rochester, Kent, on 25 April[REF] 1963 after suffering a heart attack whilst running for the train to see his daughter Imogen appear in a Royal Ballet School performance at Covent Garden.