Bonnie Doone at 339-365 Tarletons, Road, Rockbank, is significant as a predominantly intact example of a Federation style. Built in 1906 for Mr Irwin Gillespie, the house is in good condition. The galvanised corrugated steel stable, other outbuildings, underground tank and dry stone walls also contribute to the significance of the place. It is also significant as a representative example of the farms created as a result of the break up of the Clarke pastoral estate, a watershed in the history of the Shire of Melton.
Bonnie Doone at 339-365 Tarletons Road is architecturally significant at a LOCAL level (AHC D.2). It demonstrates original design qualities of a Federation style. These qualities include the steeply pitched hipped roof forms, together with the broken back return verandah. Other intact or appropriate qualities include the single storey height, asymmetrical composition, horizontal timber weatherboard wall cladding, galvanised corrugated steel roof cladding, two red brick chimneys with rendered and projecting tops and terra cotta pots, modest eaves with exposed timber rafters, turned timber verandah posts with decorative brackets and timber fretwork valance, timber verandah floor, and the timber framed doorway with timber door, sidelight and highlight. The galvanised corrugated steel outbuilding and underground tank also contribute to the significance of the place.
Bonnie Doone at 339-365 Tarletons Road is historically significant at a LOCAL level (AHC A4). It is one of the larger of the surviving rural weatherboard houses built in the first few decades of the twentieth century which express the increasing rural prosperity and historic changes of the era, and in particular the break-up of the large pastoral estates throughout Australia. The break-up of Sir RHT Clarke's massive Rockbank estate represented a major turning point in the history of the Shire. The property is also significant for its association with the locally prominent Gillespie and Tarleton families.
Overall, Bonnie Doone at 339-365 Tarletons Road is of LOCAL significance.