The seller call this a "true barn find". That's about all the info he gives.
Looking at the pictures, this looks to be in pretty good shape. There's no seriuos rust or accident damage. There is no mention of the interior's condition or a picture of it. There is a picture of the engine bay which, uh, pretty much shows us that there is an engine this car, but not much else.
Personally, I'd hold out for a 3500S P6, but the 4 cylinder cars are a bit more reliable and somewhat more plentiful worldwide.
Based on the number of hits this site gest every time I post a Rover, I suspect the seller will soon regret leaving his phone number in the listing. The P6, while hard to find in North America, seems to have a good sized fan base here.
Located in Pittsburgh, PA, click here to see the eBay listing. This is a no reserve auction.
The Rover P6 Club is a good source of P6 information.