He is best known for designing the Daleks,[3] a race of aliens who move around in tank-like travel machines, for the science fiction television series Doctor Who.

Born in the Lambeth district of London, Cusick became interested in engineering while still at art school and began attending evening classes.

[1] Cusick worked on other BBC television programmes including The Pallisers, The Duchess of Duke Street, On Giant's Shoulders, When the Boat Comes In, Rentaghost and Miss Marple.

[6] When Cusick left Doctor Who in 1966, unhappy with the lack of recognition he had received for his work on the series, the show's producer and head designer did arrange for the BBC to recognise his contribution with an ex-gratia payment of around £100.

After retiring as an art director for the BBC in 1988,[3] his hobby was writing about battles from the Napoleonic era—he contributed to a number of specialist magazines and periodicals on the subject.