Couple of things, we all walk around our house naked at times with no worries. No 1 son called 13 and 1/2 (for those of you who remeber) is a bit more restrained nowadays. Freja aged 9 takes her clothes off anywhere ! And is happy doing so, beaches, paddling pools-surely if there is a sin (not getting religious) it is in the eye of the beholder !

But the main part of this is;

When I was a trainee teacher we took a party of mixed sex, mixed up kids potholing. In order for safe and moral reasons, the teacher in charge (not me) sent the girls to get changed at the back of the mini bus with the doors open to protect from prying eyes of the boys.
All went well, all changed, no problems. about 5 minutes later a couple of old men walked down the hill and got to the minibus. They stopped and said "Thankyou very much, you've just made 2 old men very happy." "We were bird watching in the hide just over there" About 100 meteres away!!!!