Ah, yes... the magic word is "twin", implying that the cable is 2-core.
I was thinking about bidding on them, just to find out which of the drop-lead wires are being brought out on the flying lead, but it's most likely to be the pressel line and earth.
Ignore the rest of this, see next post.
(Might, I suppose, be Phones & Earth for a loudspeaker, but I reckon it's for an early morse key for the WS62 or similar set that you can key via the pressel switch - requires having all the transmit voltages present and a fast enough keying relay, which does fit the WS62.)
Chris.