The Old Post Office House was built in 1889 as a weekender for the Gengouet-Smith family who were leading citizens of Melbourne. It became the Beaconsfield Post Office in 1916 after it was purchased by the Craven sisters Belinda, Mattie and Alice. They were very active in the community and donated the money for the gates and sign to Beaconsfield Park, erected in 1939 as a memorial to those who served in the Great War.
In 1936 the Roberts family took over the Post Office. Kath and her husband Mac were later helped by their two daughters Pat and Mary. They had previously run the stores on the highway and on the corner of Woods Street. The Post Office was very busy and Bill Watts also worked there, sleeping by the switchboard at night as it was a 24 hour telephone exchange. There were two mails in by day and two mails out by rail each day. The mail was then taken to Upper Beaconsfield and Guys Hill and sorted for the private bags. When war came Bill Watts joined the Army and the girls helped their parents. The Post Office was also an agency for the Commonwealth Bank. When petrol rationing came in, petrol tickets had to be collected from the Post Office, pensions were paid fortnightly and many people had the phone connected.
Kath left the Post Office in 1956 after her husband died. Kath Roberts Reserve in Kathleen Court was named after her in 1989. The Post Office was operated by a number of people including Mr. Charles, John Matthews, Olive Bartlett, Alice Daniel, Mary Holohan, Valerie Doherty and Betty Edwards. From 1978 Mary Booth became the Postmistress and continued faithfully serving Beaconsfield until 2004 when she retired. The Post Office moved into new premises in Beaconsfield Plaza. The Post Office operated at the Woods Street site for 88 years and represented three generations.
The original Old Post Office House which served as a Post Office and home for Post Office families has a heritage overlay as part of the Woods Street Commercial and Civic Precinct cited in the Cardinia Shire Heritage Study by Graeme Butler 1996. This building is currently endangered due to an application for a planning permit to allow demolition. Beaconsfield Progress Association has a policy of supporting the history of Beaconsfield and protection of Heritage listed buildings.