He was born at his parents' flour mill on Preston River at Picton, near Bunbury, Western Australia.
[1][2] In 1874,[2] Forrest drove a mob of sheep to a new lease of land (granted to Forrest, his brothers John and Alexander, and Septimus Burt) known as Minderoo, in the Ashburton district, and subsequently became the manager of the new station.
In 1881, Forrest married Mary Parker at York,[2] after a seven-year engagement.
One of his sons, Mervyn Forrest, took over the family's pastoral interests, and like his father became a member of parliament.
[3] Forrest retired to Claremont, and died in 1917 at his residence, "Minderoo".