Forbes senior had built his own telescope and shared his interest in astronomy with his son.
[1][2] Forbes was educated in Scotland and moved to the Cape Colony, South Africa in 1896.
He stayed in Woodstock, Cape Town where he worked as a builder until 1907 when he returned to Scotland to study architecture.
[3] He lived in Rosebank, Cape Town where he built a 200mm reflecting telescope and a small observatory at his house, Craigie Brae which was in Liesbeek Road.
In 1956 he returned to Cape Town owing to ill health[7] and lived with his niece, Mrs. Hewiston[1] until his death in 1959.