The UKCS site directory has a location map, you can click on satellite view to see details of the CS for trees etc.
The directory also has its postcode CV35 0PJ, if you put that into Google maps you can then get directions too (as you know already).
Can you get Apple maps up via duckduckgo search (what i use), that shows 2 vans in the field as opposed to none on google maps.
Anyway, if you look on google map on Walton lane after the first couple houses and block of trees there are3 small fields directly off the lane, its the last field with a wide entrance.
A google search shows its listed under the Freedom camping club, so perhaps why C&CC club don't know about it?
CCC has its address, phone, email, directions; grass pitch, EHU, pets welcome, open site, pitch fees etc. Can’t think what additional information is lacking?
Found it now, much nearer the village so you come at it from the A422, off Kineton Road to Walton Lane and it's on the left. The owner replied promptly to my email.
I cycle round there quite a lot and can't recall seeing the sign - but I know CCC signs are not always as prominent as the CAMC cl ones.
You would definitely need to approach from Pillerton Priors village - the road is very narrow going toward the Fosse. Expect this would be in the directions anyway.
There are some very busy working farms around there if that would be of concern - lots of livestock in the fields close to the site so dog walking would need to be on a lead. More footpaths towards Pillerton Hersey and back towards Butlers Marston.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.