I have now managed to establish the VPN, I'm connecting a 2800 behind ADSL and a 2820 behind the dongle.

The VPN establishes its self. On the 2820 in the connection management window I can see the remote IP address and the virtual IP of the network sitting behind the ADSL router,

However on the 2800 in the connection management window I can see the correct internet facing IP, but the virtual network also shows the same IP address and not the private range sitting behind the dongle.

Hence when I try a trace route no packets get through. Any idea's guys ?

Make sure the profile is set as Route in the bottom right section rather than NAT, with the 2800's profile set to Private IP in the same section. If that doesn't help then re-doing the profile might make a difference.

Thats done the trick, that must have been about the only permutation of options I haven't tried over the last couple of days.