2021 Heritage Impact Statement - 50 Hillcrest Ave, Gladesville The Isler Estate subdivision. [SLNSW: Isler Park Estate Subdivision Plan, Sydney: Henry F. Halloran & Co., 1913, Call Number 089 - Z/SP/G4/67] ArchitecturalSydney - NorthernHeritage Assessment Author: Dr Sue Rosen Client: Shore Architects This Heritage Impact Statement assesses the impact of a rear first floor addition on the heritage qualities of Hunters Hill Heritage Conservation Area 2, ‘The Isler’, and on No. 50 Hillcrest Avenue as a Schedule 7 contributory item to the HCA.