He was born in London, England, and started his career as a child actor; among his most notable roles, was that of the ill-fated boy Stevie in the Alfred Hitchcock film Sabotage (1936).
Tester's characters were often doomed to untimely deaths in such early films as Carol Reed's Midshipman Easy (1935), Tudor Rose (1936), The Stars Look Down (1939) and Sabotage.
As television broadcasting began in Australia, Tester soon found work hosting the localized version of panel game show What's My Line?
He spent fifteen years at Channel Nine, taking charge of children's programming, and became more involved behind the scenes in production and publicity.
[2] He married Evelyn Stuart and had five children – Jolyon (deceased), Dermot, Giles, Toby and Simon and five grandchildren – Sally, Daisy, Sam, Georgia, and Max.