My grateful thanks to JM, Gerry, Whiteout, CupofLife, BillyBlue, Ros, DawnM et al. With all this wonderful help I have now found that Charles Sydney Bennett's birth was registered in Queensland 1865 as Charles Sydney Inches Father George Sydney Inches Mother Mary Ann Bennett. I will now apply for this certificate plus a death certificate for George Sydney Inches who died in Queensland in 1881. Seems George was the son of a Dr Charles Inches, RN so more research to do on this.
Doesn't help with the unknown skeleton though, he still remains a mystery. I wouldn't be at all surprised to find that R J Inches of Bathurst is a brother or nephew of George. Very curious death, he must have fallen overboard from a ship on his way home from the Boer War as he drowned off Tasmania. I also have not found how George Sydney Inches came to Australia but I wouldn't be surprised to find he had been married to someone else before becoming involved with Marianne Bennett. The family always thought Walter Bennett had left her but it could have been that she ran away with G S Inches.
Once again my thanks to all the wonderful people on this forum,
Annie