My wife and I traveled to southern/central England for two weeks in Sept. 2014. The cost of visiting the sites we wanted to see was getting high so I began researching options. The VisitBritain website advertises Hudson's Heritage Explorer Pass. It seems expensive at $185/person but when you add up the admission charges at the sites you're visiting, it may be worthwhile. On our trip, it covered the Royal Pavillion in Brighton, the Fishbourne Roman Villa, the Portsmouth Historic Dockyard, and the Roman Baths in Bath just to name a few of the highlights. It nicely supplemented my National Trust membership ($83.50 through their US affiliate, the Royal Oak Foundation). National Trust membership also includes a windshield sticker for parking in their lots. The only downside of the Hudson's pass is that they only give you a voucher which you must then redeem for the pass at their redemption centers. For me, that was only a minor inconvenience. The nearest redemption center to Heathrow is a 15-20 minute drive to the Windsor Travel Information booth across from the Castle.