Way back in ancient history, at least as far as pool playing goes, the Brits were the first to incorporate leather tips on their cue sticks. Prior to that the sticks were just that, pieces of wood with a preferably rounded tip that were used to strike the cue ball. The noise and vibration must have been unbearable in those days. Some unknown but insightful British player used chalk to make his "stick" play better. This probably caught on rather rapidly as he kicked the tar out of his opponents on a daily basis. That extra vestige of control would have given him a tremendous advantage over the opponents of the time.
In a search for better ways to control the cue ball some other, or perhaps the same, individual added a piece of leather to the end of his stick and gained another measure of control and better feel for how hard to hit the cue thus improving his position play by an order of magnitude. Another invention that would have become very popular in short order.
Do you suppose these two, assuming they were different individuals, met in a tournament and saw the advantage to the other's methods? Kind of like Reese's pieces ads of a decade ago, "You got your leather tip in my chalk! " "No! You got chalk on my leather tip!". In either case the benefits achieved through cue control were instantly recognized, I am sure.
From this marriage came the ability to put spin on the cue ball, further enhancing control of both shot making and position play for ensuing shots.
One could call this the birth of the Hustler but I am sure that began eons before.
Eventually someone with a chalk covered, leather tipped cue made his way to the pool halls of New York City and proceeded to give the locals something to think about as they ponied up good money upon losing game after game.
It didn't take anyone long to recognize the benefits of this new way to play pool, snooker, or billiards. However, the locals, being from New York and being not really appreciative of anything from the British Empire, made snide remarks every time somebody would attempt to play spin. "You're playing English!" was probably not a compliment.
And that is how the term English came to mean applying side spin on a cue ball for additional control.
It was a snide remark made to insult the one utilizing it, in order to get him to stop I'm sure.