Cheers Les. It's good to know this one is easy to find.
I know its all part of the fun but (for everyone else's amusement) finding entrances can get tedious at times....
I'll never forget one of our trips to Wales where we didn't ask how to find the hole, left the car in what was apparently the closest bit of road (lesson learnt, use a map rather than sat nav), wading up a river for an hour to find we were still a hundred yards away from the entrance and at the bottom of a waterfall which didn't look friendly enough to climb. Other things may have happened whilst working out how to get up the waterfall (phone destroyed, camera requiring much airing cupboard, bum gravy and hence improvised bog roll required). Sometime later we were please to find the car still had 4 wheels and no additional ventilation. Yes the river was entertaining, and we got wet & dirty (one person more dirty than the rest), but there was way too much daylight for my liking.
And then there was our 'first' trip to Mangle, a fine 2hr walk around Sandford hill in the middle of the summer, dressed in lots of caving kit (whilst everyone else seemed to be in shorts and teeshirt) carrying a fine selection of ladders & rope. We got wet and smelly but our lights seemed much brighter than usual that day and the cavern was so vast there even seemed to be trees growing. I'm sure several of the dog walkers we passed more than once were suitably amused.
Have learnt the lesson the hard way several times - ask for directions rather than relying on GR's / descriptions in the guide books.