I think it’s a lot longer than that. Certainly goes back to the late 70’s or early 80’s when the fence went up in the Shed and the City End become our home end. We tended to shoot that way in the 2nd half. It might even have been earlier.
As mentioned by the Duke, Caldwell tried swapping (and the dugouts) which might have continued if we’d been successful under him.
I sit in the City End of the JH as do a large majority & would have no problem with swapping but it would probably mean a lot of people changing seats to go nearer the JL for it to succeed. Many have probably sat in the same seat since the JH opened so may be reluctant to move.