Paid a quick visit to this place recently, there's not really a lot to see, some of the gun emplacements and and parts of the command centre have become completely overgrown, other parts are being used as stables and farm storage areas, there is still one gun emplacement that's not overgrown and is easily accessible.
The Penketh gun site was a reused WW2 3.7" heavy anti-aircraft gun site. Four new 3.7" emplacements were provided laid out in an arc. In addition some of the earlier emplacements were modified and reused. The post war emplacements are eight sided in plan with two of the sides open for access.
On the centre of each emplacement there is a gun mounting (holdfast) and four open ended lockers on the side walls for ammunition storage. (WW2 emplacements had six lockers) Two rooms were provided on the outside of the emplacement, one was a small crew shelter and the other an engine room with a motor driving a hydraulic pump for training, elevation and the automatic ammunition loading machinery.
More information and history can be found following this link:
http://www.subbrit.org.uk/rsg/sites/...haa/index.html
The large building at the front was apparently a battery farm, old maps show a rail line running through the site, so I assume the tall brick T shaped building was a water tank for steam trains.
.... be careful out there