Rosny was named for a family name of W.A. Bethune, the holder of the original grant on the point, and he named it after his ancestor, the Duc de Maximilien de Bethune Sully, of Rosny-sur-Seine near Mantes in France [REF].
Rosny Park has grown dramatically in the last half of the 20th century from being a small commercial precinct serving the nearby suburbs of Rosny, Montagu Bay, Warrane and Mornington to replacing nearby Bellerive as Clarence's primary commercial service district, or CBD.