Ah, this terrible term "bluestone"!! From all the work done by Rob Ixer, Richard bevins, Olwen Williams-Thorpe and many others over the past 20 years, there is now no doubt that there are at least 20 and maybe as many as 30 different stone types (and that means locations as well) represented in the "Bluestone" collection -- stones, chips, flakes and monoliths of all shapes and sizes -- at Stonehenge and in the broader neighbourhood. There are spotted dolerites, unspotted dolerites, ashes, shales, rhyolites, limestones, sandstones etc etc...... in my book they are ALL glacial erratics, maybe even including some of the sarsens, some of which could also have come from the west. This looks to me like a litter or scatter of stones spread over a wide area. There is (as yet) no sign of anything we might call a moraine, but glaciers don't always leave moraines where we would like them to be -- to the best of my knowledge, there is nothing anywhere in the UK that could be designated as a moraine marking the outermost extent of the Anglian ice that affected the UK around 450,000 years ago.
To those who are still inclined towards the human transport theory, and would like to think that our ancestors hauled stones from up to 30 different locations all the way to Stonehenge, why were all of these locations in the west? Why were there none thought to be suitable in the south, north or east? My answer is that they simply collected up whatever stones they could find, many of which happen to have been brought into the area by the Irish Sea Glacier.