The setup is;
Bonded ADSL line in with about a dozen usable IP addresses.
About 18 internal vLans (which must be totally closed from each other - except for the fact that one, vLan64, has to be available from all the other vLans).
Most of the vLans will have a dedicated public IP address, but a few will have to share.
And I need to get this working today (it's 1220 here in England)!!