Lots of things are possible -- with enough people over a long-enough time frame.
As an alternate possibility, how cold might British winters been at the time? Instead of stone balls, could they have poured water along the path, had it freeze, and had a huge party at the winter solstice, moving the stones a couple of miles every year until they were done?
FOUR SECONDS APART!!!!
I’m going with ICY paths;) LOL!