For what it may be worth to you, the family Bible gives a Henry Greenland born June 19th 1772 (presumably in Westbury). That's all I know about him. He would have been of an age to be in Aust. in the early 1800s.
I believe my great-grandfather, James, b. 1866 (Westbury), spent some time in Aust. as a young man, but had returned to the UK before 1892 when my grandfather was born.