Oooooh. So near yet so far away as the song goes...

The A to C adapters are great and at about £5 for 3 on Amazon I am keeping them. Plug that in and the Apple thuderbolt 2 to 3 cable and Windows recognises it. Am I on to a winner thought I!

No. Plug the monitor in and Windows can see it but doesn't know what it is :-(

It does give me hope though that a new laptop (like my son has) with a USB C port may just be able to do ALT Dp mode on the USB. We can only hope...