Found this which might be of help to others with other makes ...
http://www.alpha-bid.com/media/Shared-Pics/OBD2_protocols.pdfIt seems to put our Golf around the change from ISO 9141 to CAN-Bus.
Interesting that all cars of all makes, everywhere after 2008, are CAN-Bus, although from what I've read, there are still different flavours of this ... nothing's ever simple!