Sorry Moss -- don't go along with this "tantalizing evidence" idea at all. Tidal streams and tide races, and rapid river flows, caused mayhem in the Millennium Stone project, causing the bluestone to end up on the bed of Milford Haven. And there has been endless speculation about trade routes, passing traders noticing spotted dolerite etc. Remember that there are at least 20 different rock types in the Stonehenge bluestone assemblage. Why would anybody want to pick up all those "rubbish stones" just because they saw some pretty ones as they passed along a ridgeway?

As far as I'm concerned this is all circular reasoning: they could have done it, therefore they might have done it, therefore they possibly did do it, therefore it probably happened.........

The off Bronze Age boat doesn't tell us much either -- remember we are talking about the Early Neolithic here.