Thanks for the information Rex.
I've not been able to find Richard on the Royal Albert passenger list for 1856/1857, so I e-mailed the State Library of South Australia. Their reply was that there was a John Trevivian & wife on board the Royal Albert, arriving 29 Mar 1857, but no Richard.
They also supplied me with some death dates of various Richard Trevivian's all living Wallaroo mines. None of which appear to be the Richard born c1835 who was suposed to be on the Royal Albert in 1857
So now I'm totally confused !!
Anyway, thanks again for your help.
Sue