The name Mill Park dates back as far as 1841 when George Coulstock named his farm Mill Park after a water-driven mill he had begun to build on the Plenty River. Coulstock died in 1842, however, leaving the mill unfinished. It was 1848 before the Janefield Mill finally opened for business, operated by Peter Hurlstone.
Janefield was the village where Mill Park and various other farms were located. During the early 1850s, Janefield consisted of the Plough Inn, a post office, blacksmith’s shop, church, school and the mill. The mill had closed by the late 1850s but a fine bluestone Presbyterian Church was built in 1861. The Morang Roads Board had also installed a tollgate near the Plough Inn to raise funds from travellers using the Upper Plenty Road, as it was then known. Today it is named Plenty Road.