In the inter-war years West Sydney or Western Suburbs or western suburbs or western Sydney meant what we now call the Inner West. The earliest use of Western Sydney (with capital W and S) that I have so far found is in 1961 when Prospect County Council used the term to describe the region in which its distributed electricity. In a 1962 advertisement (Nepean Times 18 October 1962) the County Council included a map of Western Sydney where it supplied 114,000 consumers in the Parramatta, Penrith, Liverpool, Blacktown, Fairfield, Holroyd, Windsor, Baulkham Hills and Colo council areas. Interestingly, they did not include Camden, Campbelltown and Picton areas.

Much more work to do, but Western Sydney as a place name is, I think, historically quite recent and, as you note, contested in many places to which it is applied. I would like to look at the decline of Cumberland as a regional name (the County of Cumberland was formally established on 4 June 1788) and its replacement with Western Sydney – I suspect the relationship is not that simple or straight forward. I wonder if Cumberland will rise again once day to indicate a region with its own identity rather than being an appendage of Sydney as the name Western/western/west Sydney implies, and perhaps a name which its constituent areas could more readily identify with? Cumberland International Airport anyone!