It seems like there's some confusion here. "Puffin' Billy" is actually a nickname that refers to several different steam locomotives, not just one specific engine. While it's not the name of the last operating steam locomotive on the British Rail system, it has been used colloquially for various engines, including those on preserved railways and even as a marketing title in Australia, as you mentioned. The term "Puffin' Billy" has a nostalgic and whimsical geometry dash association with steam locomotives in general, rather than being tied to a single historical engine.