I see there is a debate on where to go afterwards.
Personally, I would not wish to drive anywhere within 1 to 2 hours of the finish, due to the chaos leaving the carparks, nor would I wish to navigate a route 2 miles to a pub on foot, and then 2 miles back to the carpark, just for a drink.
Let's face it, only the diehards will bother, and it'll fizzle out as people turn their attention to getting home afterwards.
It would be better to meet at the licensed beer tent on the site, so there will be no walking/driving problems, and there is a chance most people are then likely to look in.