Hi there,
I doubt we have a connection, but I have a mysterious Benjamin Thorpe in my family. He was born cir 1820s, and married Elizabeth Smith in Gawler, South Australia, Sept 1853. I believe they had 4 children, Thomas John, John Howard, Henry (Harry) William Benjamin and Elizabeth Smith Thorpe.
I have no idea where Benjamin is from, he's so evasive! I can't even find a death record for him in South Australia, neither can I find an immigration record for him in SA. Do you think it's possible he's a son of your Benjamin and he came across from Fremantle? I think it's a long-shot, but it never hurts to ask!
Thanks,
Lauren