There have never been any access controls on trips to Swildons Sump 1, or any other part of Swildons Hole so why are you suggesting there were?
Apologies, I didn't make that clear and I'm mixing up two differing restrictions. The issue with Dad taking groups into Swildons related to what caves his LCMLA ticket allowed (I think the upper series is included now and may have been back then but he certainly didn't have it). I know that's an unrelated restriction and not for this discussion. The fact remains Prid in Devon was by far the most impressive cave (I think it's way better than Goatchurch) Dad was able to take teenagers to. As I mentioned we used to do sump 1 and back as a personal trip regularly.
There are many Mendip caves with open access and just a few of the better preserved have access controls over and above the freely available CSCC key system.
The CSCC key might be readily available but doesn't make caving easy - I have access to one via the club I'm a member of but... If I want to visit Hillier / Fairy I have to drive 10 miles past the cave, pick up a key, drive 10 miles back to the cave and then repeat this 20 mile round trip afterwards (though the afterwards is more worthwhile for the showers). This adds 1h20 of time to the day and 40 miles. Given that it's already 1h30 drive and 50 miles from home (Poole) it's rather annoying. Yes I'm aware I could go in Fairy & out Hilliers without a key but it's better the other way around particularly if you find one of your team don't fit through the squeeze at the connection (which has happened). So in my opinion the CSCC key is a pain in the butt and serves little purpose in this instance as the whole cave can be accessed without the key providing you don't eat too many pies. I've just picked this as an example as it's the one that annoys me the most. The same principal applies elsewhere.
Please don't think I'm anti conservation in Fairy Quarry as I think the system for Shatter and Withyhill on the other hand is appropriate, but then I think all who visit these sites will appreciate just how vulnerable and special they are.
In terms of conservation in general - if you don't want others to enjoy the caves (which does bring a small risk of some things being vandalised by a minority as per HLIS) then either don't discover them in the first place or empty a lorry load of concrete into the entrance immediately after discovery. Just out of interest who breaks the most stal and leave the most mess on Mendip - vandals or diggers? Based on the amount of broken stal I've seen in spoil heaps near digs and the number of manky old tools, buckets, scaffold etc lying around I suspect those with the bang win by a long way. I'm not saying this is wrong - in fact please keep finding me new caves to visit - but in my opinion the most destructive phase is the discovery and not the occasional accident or even more occasional deliberate act afterwards.
On a more positive note, for those who also find keys a pain, here are my hassle free Mendip recommendations...
Mangle Hole - yes it muddy but a very enjoyable (until you get to the cleaning afterwards bit)
Welsh's Green - not as bad as it's reputation and well worth a visit
Lionels Hole
Honeymeads (when the air is good)
Swildons
Eastwater
Manor farm (when the air is good)
Baths / Rods
Thrupe Lane (when it's not blocked)