Thanks for clearing that up, Chris.
Just to follow up, when I got down to the socket and scraped 3+ layers of emulsion off it, I discovered that it is a NTE5 Master so I was able to connect my extension cable straight into the back.
Rather flukey too. My old IDC plastic tool was a bit beyond use, to say the least, so I jumped into the car to go and see if the village lecky shop had one. On the way off the Park where we live, I spotted an Open Reach chap just about to check out a telegraph pole and asked if he knew where I might get a new tool from. He went to his van and gave me a brand new Krone IDC tool. I asked him how much and he said I owed him a pint if I ever saw him in a pub. Very Nice Man and wasn't I jammy?
All problems solved for now. Thanks everyone.
dave