This is the same obelisk shown in the previous post. The artist, Conrad Martens, was born in London. He later sailed briefly with Charles Darwin on the Beagle (and by all accounts became a lifelong friend), but left that voyage in 1834. He arrived in Sydney in 1835, and settled permanently in Australia. Jon, his biography notes the following:
Martens had a liking for the North Shore of Sydney with its panoramic vistas of the harbour and foreshores, and in 1844 built a house at St Leonard's.
Readers of the blog should note that St. Leonard's is the North Shore neighborhood in which the blog resided while in Sydney.