In ye olden days, when I was a child (I do remember this) and decimal coinage was still just over the horizon, public lavatories were accessed by paying a penny. This was the old English penny, from the days of Pounds, Shillings and Pence. It was a big, heavy coin, reproduced here around 10% larger than life-sized.
Once decimal coinage came in at the start of the 1970s, the only similarly-sized coin was the two pence piece. So all of the loos were converted.
But Oh, how inflation has caught up with the public bog. I saw today that the toilets at major London rail terminals like Euston, Paddington and Victoria have all just put their entry prices up to 30p. Thirty whole pence! Nearly a third of a quid just to empty your bladder!
Outrageous. I walked outside and used the nearby McDonald's.
Social satire? Or biological necessity? You decide.