After calling 21 Hopetoun Avenue home for nearly two decades, healthcare industry veteran David Armstrong and his wife Kirsten have decided it’s time to downsize and have placed their impressive Mosman residence on the market.
The property, nestled in Mosman’s prestigious Golden Triangle, comes with a $22 million guide price and represents one of the area’s more substantial offerings this spring selling season, according to listing agent Michael Coombs from Atlas Lower North Shore.
The Armstrong family’s four-bedroom, five-bathroom home spans four levels and showcases 645 square metres of internal living space on a 544 square metre block. The residence takes full advantage of its north-facing orientation, offering sweeping views across Chinamans Beach to Clontarf.
What sets this property apart is its hotel-like grandeur and entertainment capabilities. The home features a dedicated entertainment level complete with wet bar, games room, fully equipped cinema with automated acoustic curtains, and distinctive porthole windows that provide underwater glimpses into the mineral saltwater pool.
The main living level houses a marble kitchen fitted with Miele appliances, multiple living areas, and opens onto a courtyard featuring water features and an all-weather automatic awning system. The design allows for seamless indoor-outdoor entertaining, whether hosting intimate dinner parties or larger gatherings of up to 50 guests.
A custom six-person lift services three levels of the home, whilst the top floor is dedicated to rest and relaxation with three bedrooms, each featuring private ensuite bathrooms, plus a library and additional courtyard space with harbour views.
The property’s lower level provides practical luxury with a four-car garage offering street-level access and an impressive wine cellar capable of storing 1,500 bottles.
Throughout their renovation, the Armstrongs worked with award-winning builders Total Co-ordination, engaged Corben Architects for design work, and enlisted Carlos Correa Design for interior styling. The result incorporates high-end joinery, extensive natural stone, comprehensive home automation, security systems, audio-visual integration throughout, air conditioning, heated floors, and gas fireplaces.
The location places residents within easy walking distance of both Chinamans Beach and the Balmoral esplanade, making it particularly attractive to families seeking a coastal lifestyle with city convenience.
David Armstrong brings extensive experience from the aged care sector, having founded the Amity Group, which was later acquired by British healthcare company BUPA in 2007 for $1.2 billion. His background in healthcare has informed many of the thoughtful accessibility features incorporated throughout the residence.
The property represents a significant addition to Mosman’s spring property market, particularly within the sought-after Golden Triangle precinct. With Mosman’s median house sale price sitting at $5.5 million over the past 12 months, this listing positions itself at the premium end of the local market.
For the Armstrongs, the sale marks the end of a chapter in their family home, as they transition to a new phase of life requiring less space but no compromise on luxury and convenience.
Published 4-September-2025
