My parents had allowed me to go to the town library on my own from 8, but at 10 they let me start going swimming alone.

Now I'll point out at this point that when I went with my father we always went in a pool that had cubicles down the side, always wore our trunks under our clothes, and when we got out DESPITE BEING IN A CUBICLE OUT OF PUBLIC VIEW he would wrap a towel around me, one round himself, and we did the towel dance to get our trunks off, dried, and dressed...

They made me promise that I would go to the same pool, and cover myself while changing. 

Our town baths had four pools, the training pool where I learned to swim, the 'gents' and 'ladies', although they were unisex by the late 60s, and the gala pool which had separate male and female changing rooms.

Honestly,  I was going to the cubicle 'gents' pool until I met a schoolfriend and his parents outside the baths and he said "come in the gala pool with us".

I walked into the changing room.....

There were thousands of naked males, from toddlers to pensioners, so much pubic hair you could have filled a duvet, and nobody was bothered about their nudity. (Okay, maybe my 10 yr old mind exaggerated a dozen to thousands, but I'd never seen live men before. It felt like I stared for hours but can only have been the time it took me to strip my tshirt, shorts, and sandals off before we went to the pool.)

At some point of the swim my mate and his parents left, so when I returned to the changing room I was alone.

We only had a bath at home, I had never had a shower before, so I wrapped a towel around myself, took my trunks off, went to the showers, towel off, wash myself, wrapped towel around again, two steps.... why was I wearing a towel? I'd just been naked with about 50 men (okay, two), and they weren't concerned about either their or my nudity... the towel came off, I walked back to my clothes, and took a long time drying myself and dressing.

It felt so natural, not in the slightest bit wrong.

I never went back to the 'gents' pool unless the gala pool was shut, most Saturday mornings, and two or three times a week in the holidays. It very soon got to be that I was spending more time naked in the changing room than in trunks in the pool.