My latest postcard acquisition.

The Iron Pot is a chunk of rock at the mouth of the Derwent. The lighthouse "is significant for several reasons. It was the first lighthouse built in Tasmania, it is the second oldest lighthouse built in Australia, it is the oldest original tower in Australia, it was the first to utilise a locally made optic, and was the first Australian lighthouse to use solar power."
From
Lighthouses of Australia which has more pictures and information about the island, like the gold rush of 1862.
So the big house was built about 1885 (two storey so there was room for it) and demolished about 1921. This postcard is probably about 1910, as it's similar to others I have that are dated.
As it is now:
( From 2005 )