Hello yet again!
Just to say that I've finally opened up both of my extension sockets, and both are wired exactly the same as my old style faceplate, with all six wires connected to exactly the same terminals!
So, in my ignorance it seems that, unless mine is the only house in the known universe that has four wires coming into it, I can safely disconnect the Green/white and White/green , as well as of couse the Orange/white and White/orange. (What a rat's nest of disconnected wires I'm going to have!)
Or should I for whatever reason try to find a modern faceplate with four terminals and leave the Green/white and White/green connected?
Cheers,
Mark