Crawcrook appears to be Gateshead, Durham?
It's possible that Jonty was his given name, but it was also a nickname for Jonathan. If he was a John, I think you might be more spoiled for choice. Finding his birth entry for his official name and year of birth might help you.
I do feel inclined to ask if you know for certain that he's no longer alive? It's not likely, but the sister of one of my ancestors has just become a centenarian.