Chertsey is a film studio (although known as Longcross), the test track is on the other side of the M3. Hurn used to lease a portion of the site for commercial driver training a while back, but it was discontinued due to health and safety concerns. It's always been a vehicle test and evaluation site, in fact it was where I first saw Ajax running around! It closed recently and I wondered if the testing might have moved to Longcross but apparently it's gone to Milbrook.
Andy