Perhaps the owner didn't fit the plaque as the final 15 weren't delivered with the plaque attached. I received mine a couple of months after I took delivery of the car with instructions on where to place it on the glovebox lid.
You mention No4 and No6 above, what are you saying? 4th and 6th from last UK spec cars? I have the certificate of provenance from Lotus and my car is 8th from last. My car came of the production line after the Stratton 7 cars were delivered and they were supposed to be last of the line!
My car had the outer exhaust configuration when delivered but I didn't think it sounded like a V8 so I changed mine for the Lotus Federal Exhaust and the "cheese grater" rear valance. As far as I can recall the final edition European and Federal cars were delivered with the centre exhaust.
The price of these cars is only going one way and I think £65k is a fair price to be asking for a low mileage car.