Hmm, just read through this whole thread with a bit of dread as i pick up my new van in a couple of weeks.... will have to weigh it and see where i get to.
Totally follow the dual purpose argument, makes perfect sense. But what i don't get is the concept of a double offence, of exceeding both the national speed limit and the speed limit for a vehicle (see post 69 above, for example). Surely exceeding the speed limit is one offence, and that limit can be lower (on dual or single carriageway) if it's a not with the dual purpose classification? How do you get to two separate offences?