I have relented. One last ditch attempt. I have ordered a new USB 3 card. My old one was 3.0 with only A connectors. The new one is 3.1 Gen 2 with an A and a C. That was not expensove so, whether it works or not I will stick with it. I have odered the official Apple 3 to 2 cable for £27. If it doesn't work, I can send it back. Should have the card tomorrow and the adapter next week so I shall update this then.