Cando - thank you so much for this information! What a sad end for both of them. Archibald had left a wife and ten children to travel to the other side of the world, presumably to try his luck in the gold rush - he must have been pretty desperate to go to such lengths.
This finally helps to understand why he disappeared from UK records and draws a line under things.
(Thank you for all your time and help with this, and I'm sorry I haven't replied earlier - unfortunately I've been preoccupied with sorting out an elderly relative who was taken into hospital this last week and also helping care for my brother who has advanced Alzheimers, so I'm afraid Rootschat has had to take a backseat for me. Thanks again for all your help!)
Regards,
Stoney