This is a harbour craft pennant for the Royal Navy Harbour Craft from the base at HMS Woolloomooloo.  

HMS Woolloomooloo was a repair base for ships of the British Pacific Fleet at Garden Island Naval Base, Woolloomooloo, Sydney, in May 1945 and was initially named HMS GOLDEN HIND II.

These flags were lightweight, made from felt so not many now survive.

An identical one is held at the Royal Navy Research Archive as part of the private collection of the effects Lieutenant A.J. Bow RNVR who served as 1st Lieutenant at HMS Woolloomooloo.

The identical flag can be viewed via royalnavyresearcharchive.org.uk and can be seen in their online gallery via the page titled "The British Pacific and East Indies Fleets, The forgotten fleets that fought the Japanese in the Pacific and Indian Oceans"

Length is just over 24 and a half inches including the tassels.

Please see pictures.