I may have told this before. Early 70s before pulse dialling on a circular dial became tone dialling. I was shown how to tap dial. Dial each digit of the number you're calling, and as the dial spins back to its start position, tap the cradle as many times as the digit you dialled. One for 1, two for 2... ten for zero. Repeat for each number you dial in turn. Connected without money. Cheers easy.
In 1976, back from Omagh, I discovered that the phone box behind Bhurtpore, Tidworth (we were next door in Aliwal. The Aliwal NAAFI was on the boundary between them, and the phone box on Coronation Street essentially adjacent, but behind Bhurtpore) still had a pulse dial phone. So every week me mum got a free SitRep.
Went away to UNFICYP for six months. Shiny new phone in the box. Tap dial home. "Hello?"
"Hello, mum. I'm back from Cyprus."
"Who is this?"
"Er, is this not Whitburn 293088?"
"No, it bloody isn't. You've called an Andover number, you're in the call box in Tidworth and tap dialling doesn't work any more. Stop bloody calling me."
I doubt they were 60 mm then.
Probably more like 54 mm or 2.12598 inches as we used to say.
Actually I think it was big soldiers as opposed to little soldiers (Airfix HO/00).