When four mop-top English lads stepped onto the tarmac at JFK International Airport in New York on February 7, 1964, America and the world changed forever, only we didn’t know it yet. After the famous Ed Sullivan show...

It was 1961. And the world was about to be spun wildly forward on its axis, not by the iron fists of Cold War strategists but by the nimble typing fingers and congeniality of one Freda Kelly.

The atmosphere around the Pop International Galleries, on Soho’s main drag, West Broadway in New York City, was prickly with expectation just before sunset on Monday, June 25. On the door was a small...