It was the middle classes who reinstated their ‘g’s. It’s not that they dropped their ‘g’s, it’s that we all didn’t pronounce the ‘g’ after the Old English period. So, [in] 1100, 1200, we were all “huntin’, shootin’, fishin’”, as indeed we mostly do around the world, in Englishes everywhere. But, the middle classes who got so upset by Thomas Sheridan and his ilk, by the prescriptivists: “Well, of course you ought to pronounce it, there’s a ‘g’ at the end of the word, so you ought to pronounce it.” So, what are we going to do, are we going to turn back the clock and say: “Well, because that was a load of rubbish, we’re all going to do just “huntin’, shootin’ fishin’”. The upper classes did until very recently – they’ve only just recently joined the middle classes there – or are we going to say: “Well, there’s a prescriptivist rule that really has put back time, as it were”?
Dr Laura Wright on Michael Rosen’s Word of Mouth, BBC Radio 4, April 14th, 2015
If you’re middle class and English you likely care about the distinction between “swimmiNG class” and “swimmiN’ class”, as uttered by your seven-year-old daughter, but not if you’re a speaker of almost any of the other Englishes around today. But as it turns out, it was introduced as an artificial convention for people insecure about their social status and intimidated by self-appointed linguistic prescriptivists. Then kept alive by the rest of us, ever since, to shore up the precious advantage we imagine it gives us over the lower orders.