I have read the useful information at
http://www.kitz.co.uk/adsl/socket.htm on fitting an NTE5 socket as first extension to an LJU master socket.
The article says (in the Telephone Cable subsection) that pin 2 connects to point B using the wire that is blue with white bands, and pin 5 to A using white with blue bands, and other sites say the same. But the section on Fitting an NTE5 Master Socket (borrowed from clarity.it) shows pin 5 connecting to B with the blue cable, and 2 to A with the white one.
This leaves me somewhat confused. I believe that it may not matter if I get the wiring the wrong way round, but it must be better to have it correctly wired.
Is the image from clarity.it wrong? It certainly seems to be in a minority among sites that list the colours.