The info is on the above page, and there is a link to the application form.
I reckon just report it to the Police as a suspicious vehicle. They will note the details and if anything dodgy will then have a reference for enquiries.
+1 on that. When someone else calls with the same thing they will have reason to investigate.
Why anyone would bother doing this when google street view is available I don't know.
The reason that its not so cut and dry in our case is that we recently applied for resolution via the Weathertight Homes Resolution Service. While we have had all pending inspections undertaken already, and the driver of the car wasn't one of the inspectors assigned to our case, I cannot rule out the driver's actions being related to this.
I was hoping there was a legal way to determine who the driver was, so I could ascertain whether I needed to be concerned or not.