My wife once said to me "Do you ever think about anything other than geocaching". I replied "That's unfair dear, I think about football quite a lot as well". She's right really, it means that when I come across something like this I think "geocache placement"!
My other cache on Runcorn Hill is a light hearted one but all this talk of Aliens should not distract you from the fascinating history of Runcorn Hill. There is an information board telling you all about it. To find out what "it" is you will have to come here and look for the cache! I would also recommend finding the rangers hut and getting a leaflet called "Over The Hill and Far Away" which points out all the interesting features on Runcorn Hill. Some of these are industrial and some are military such as the remains of an aircraft battery.