[1] Robertson was educated at Presbyterian Ladies' College, Melbourne, and learned to type and take shorthand; she later took up secretarial work.
[1][2][3] At the beginning of World War I, Robertson was travelling in Britain; she joined the British Red Cross Society and the Order of St John and offered her services.
[1][2][3] Robertson resigned from her job in December 1938, and the Victorian Division and the Central Council granted her life membership.
[1][2][3][6] In 1950, the home for seriously disabled ex-serviceman, at Clarendon Street, East Melbourne, was named Philadelphia Robertson House in her honour.
[1][2][3][10] Robertson died on 11 January 1951 in St Andrew's Hospital, East Melbourne, and was cremated according to the Presbyterian forms.