Thankyou all....

Firstly
the Charles Cave in Perth is no relation, I have encountered him in my search several times.
Ros, the house in Somerset blew my mind when i saw it the first time, just lovely!
I do have the obit, and the names are
Charles Cave (I do not know of a second name)
Susanah Darby (Susan on the gravestone)
Muss, I do not know if this is my Charles cave, there were quite a few but his son William Rendall Cave-Kendall on cert, was appointed co-liquidator of the Commercial Marine insurance Co in Aust in 1884.
I do have Charles death cert 1850 and the State Library in Adelaide provided information on a search to say he was a farmer at sturt here at that time.
Several references allude to them travelling in 1848/9. His son John Darby Cave travelled here on board the "Appleton" (2 mast brig) arriving 21 June 1849 just prior to his sister, Mary being married here.