Thanks for all the looking. I don't think we've nailed him yet though!

I think the Roger you found on the 'Thomas Arbuthnot' is too young for our Roger.

I have Roger's birth date from two distant relatives who have been doing family history for many years. He married a Margaret (Male) in 1836 and had two children with her - William and Elizabeth. She died in 1846 and Roger married Louisa Pope, nee Hine (Hyne), in 1850, (UK marriage indexes) in Devon.
There were several children of this marriage - Bessie, Kate, Blanche (our Great Grand mother), Clifton and Frederick, - all born in Devon - and Clifford, Clement, Charles, Cyrus, and Bella born in Victoria.
Roger died in 1898 and is buried in Melbourne General Cemetery, with two sons.
Roger's sister Harriet, married Francis Male and immigrated (before Roger's family) to South Australia and I think his son by his first marriage, William, went there too - but I have forgotten the details of that.