Online now!
... Let the building commence!

Well, it was a new installation anyway so I hope no one will recoil in 
horror when I say I reinstalled the system, installed userppp and 
speedtouch packages, altered the relevant files  - and it 'just worked'. 
I think I must have been over-tweaking things before. FWIW I used an 
older version of the adsl.sh script though, which is more understandable 
to me than the newer one which didn't work 'out of the box'.

*Moral of the Story?* Don't anticipate problems that may not happen - 
tweak only when 'as is' isn't working.

Thanks to all who tried to help.

Ja'far