The sites that have "(CL)" after the name are CCC certificated locations rather than proper campsites. Those that have "(CS)" are CCC certificated sites for up to 5 caravans and/or 10 tents. Either may be caravan only, not having toilet facilities.
They are officially for CCC members only, and you may not get in if you aren't a member. This will depend on whether, as I expect, there's club insurance involved that only covers members, and, if so, whether the site owner knows or cares.
CCC == Camping and Caravan Club
Richard:
The "hotel£££, hotel££, hotel£, campsites" dropdown is showing white text on a white background for me (on chrome), apart from the active or under the mouse option with a blue background.