I've already had this response (below) but have advised the chap that I will only put him in contact with you should no other likely candidate put their name forward in a day or two. Are you related to the 4th Baron Joicey?
This caught my attention because my wife is the great-great granddaughter of Gert Johannes Jacobus van der Merwe (1881-1949) who was taken POW at Paardeberg together with his father, Pieter Hendrik van der Merwe (1851-1903) and some of his brothers and all sent to St. Helena. This family was from the farm Stompoorfontein, in the Potchefstroom district.
Now the interesting part: in the family is a real violin of Gert Johannes Jacobus van der Merwe as he was a player! Coincidence?
That is amazing to think that the violin I am looking at was probably made by one of these men! GJJ vd M and JC vd M look like maybe they are brothers and GJJ vd M the father? Is there any way of finding out if they have and living descendants?
I've just read this and my spine is tingling!
Re Joicey, the current Lord Joicey, James is a cousin of mine and we are fellow trustees of The John George Joicey Museum in Newcastle. My father was John Edward Joicey, 9th Lancers and his father, grandfather and further back were all called Edward - makes family trees tricky sometimes!
It's looking increasingly like the chap who first responded to me is from the Van der Merwe family who made the violin in captivity. I have asked him to message me and will forward you his details once received. You can take it from there. Please note that I have no interest in or connection with the family. I merely "put it out there" in an effort to assist your locating the relatives.