As Frances has said, some of the Australian sites have disappeared. I used to just click on to two bookmarks - assisted and unassisted migration to Victoria. These are now gone.
Through the State Library of Victoria www.slv.vic.gov.au I picked up an 'assisted immigrants index' up to 1871, but no Thomas Maltby.
I am already seaching arrivals in NSW for someone, so I will try to pick up something for you, as I need to renew the bookmarks as well. Even BDM's in Victoria used to be easy, and now they are a user pays scenario.
I am sure other Australian researchers will try for you as well, as you folks on IOM are so helpful to us.

Cheers, Lorraine Daly Qld.