Hi, this is a bit of a stab in the dark but I have a Charles William MARTYN in my database. I am not related to him though, as he married my ggg-aunt Rose Sarah CONLAN (CONLON) in 1900. They lived around Manumbar and Goombungee, near Toowoomba, in Queensland. They had several children including Charles George (Charlie) MARTYN who died in the Great War. If any of this sounds familiar, let me know. This Charles MARTYN may be a son or grandson of your Charles William. I am simply going on the similarity in the names.