As with all ironstone mines, you need a gas meter here.
Conditions change in there dependant on weather conditions and places that are fine one day could get you into some serious trouble another day.
Yes i agree with you i have been in here 3 times now and never venture too far in for that exact reason i,m well aware of the dangers so keep very close to the entrance. Sound advice though and serves as a warning to anyone else attempting it for the first time.