Due to illness she played little tennis in 1935 and the first half of 1936.She won the Australian Championship singles in 1939, defeating Nell Hopman in straight sets.
In 1937 she was a finalist losing in the final to Nancye Wynne Bolton in three sets.
Together with Margaret Molesworth, she won three women's doubles titles at the Australian Championships in 1930, 1933, and 1934.In 1939 the Queensland Lawn Tennis Association proposed to send Westacott and May Hardcastle to the Wimbledon Championships, but Westacott declined due to illness of her mother.