Some time ago I did a piece on ropes, and I have been thinking more about this. The archaeologists want 80 or so bluestones to be moved from West Wales to Stonehenge -- and MPP now wants them to be moved not by sea but overland. He suggests that the 80 or so stones, each weighing between 2 tonnes and 4 tonnes, would have been moved entirely by pivots and levers -- which is stretching fantasy to absurd lengths, if you will forgive the pun. Maybe he has realized that "long rope" technology at the time was completely inadequate for the task of strapping big stones onto sledges or frames, or for pulling large stones across difficult terrain?
In the little research that I have done, it seems that there was some knowledge of ropes back into the Palaeolithic and the Mesolithic, but the ropemakers of the time would probably have used wild vines, brambles or nettles for the task, and to make ropes long enough and strong enought to shift a 4 tonne monolith would, I think, have been far beyond the capabilities of those early people. Some authorities say that the art of making long and thick ropes (ie involving some sort of mechanical process for twisting the strands) started in China around 2800 BC and gradually spread into Europe and eventually into Britain. On this schedule, the technology would not have been available at the time the archaeologists want big stones to have been moved from Wales to Stonehenge.
This seems to me to be an insurmountable technical hurdle.........