Loddrick your picture is a master socket the same aswoodys oicture but from the other side.
Connect the Black and Green to A and B and test the socket by plugging an old analogue phone into the test socket under the bottom half ogf the face plate.
If that doesn’t work then try the orange and white pair. (You only have two choices anyway)
If you get a dial tone then with your old phone plugged in try ringing the line. If the phone doesn’t ring then you have the correct pair but the wrong way round.
Since your ADSL appears to be on an extension the second pair must go to it. These should be connected to 2 and 5.
My guess is that this socket is the original master. An extension has been added that required a cable to another room. The engineer or (do it yourself bodger like me)has used the second pair in the cable to run the line back to the external junction box. Then they will have connected the extension pair to another cable that runs to the window where the router is.