Thanks for the replies.
I finally got it working! (thanks to the UK Moeller Product guy who e-mailed me today)
Problem was (as Mr Spok suggested) the plug pinout was wrong, even though I was using Moeller doc 02/07 AWA2528-2345, for modem connections!
To help others, the connections that work for me are below
Modem 9 pin Plug Cab cable 9 pin plug
2-----------------------------------------------------3
3-----------------------------------------------------2
5-----------------------------------------------------4 and 5
8-----------------------------------------------------7
Thanks again
Boswell