As larger machinery became essential on the farm, the stables were extended to the south west about 1900. This extension is the engine room which links the once separate stables and mill. The engine room probably housed steam, diesel and petrol engines that drove chaff cutters and other farm machinery.
To the right of the engine room is the mill. It has three floors which suggests it was originally built as a flour mill. This makes good sense because Camden Park was like a small town, with large numbers of employees and their families living on the estate. Wheat could be brought here to be ground into flour to meet the needs of the Macarthurs and their employees.
The estate had to be self-sufficient and this is why the Home Farm, now called Belgenny, included a blacksmith's shop, wheelwrights shop, pit saw, carpentry shop, engine room, shearing shed, slaughterhouse, creamery and flour mill.