Ok, so curry is most likely not the English national dish. Who knows Australia's national dish? As far as I can remember it is not shrimps on the barbie as we don't usually call them shrimps unless they are the tiny pre-cooked frozen ones you get in fried rice. I was told by a chef I worked with that it was kangaroo tail soup but I can't find anything to back that up. I would offer a list of options. Anything on a BBQ, Meat pie (most probible) , kangaroo with bush tomatoes (not likely but it certainly is very Aussie), Spaggetti bolognaise, Yiros/kebab (depending on origin).
With Australia based on a plethora of nations with large populations of, English, Italians, Greeks, Vietnamese, lebanese, Germain, Chinese, etc. Along with the originally about 500 different Aboriginal groups, The national dish might be a hard one to come up with.