Providing the car was unregistered when imported, the V5 will not shed any light on whether its an import or not.
A car is only assigned an import date when it is bough into the country as a vehicle registered to another country and then re-registered to the UK, which is what I assume is the case for Mr 'Riders Mk2
My best friend recently bought an Astra turbo cabriolet from a company that imports them from Spain. Because it came into the UK un-registered it has been registered as a UK car, even though it is clearly an import.
As far as the V5 is concerned (and any subsequent buyer) his is a UK car, as it was first registered here.
I assume Mr Riders Mk2 V5 stated it was an import because it was imported as a registered car. Had it been unregistered at the time of import, the V5 wouldn't give an imported date.
Definitely ring VW cust services, they will confirm via vin/chassis number.