IanC: I had a look for this Nigg stone, and a yahoo search on Nigg and harp threw up a site colled niggoldtrust.org.uk(I think) as the second or third hit. It offered various visuals of the stone which I couldnt access(ntl cable internet).
   I've learnt you always have to be a bit suspicious of the dates people place on these stones and other artefacts. Vague guesses by archaeologists soon get enshrined as fact. And circular arguments abound, with archaeologists relying on historians guesses, and historians relying on aechaeologists guesses, with not a great deal of evidence being included in the proceedings.
   However, it seems reasonably clear that (1) there were plenty of things called harps in use in various parts of Britain c 800AD, but (2) there is no evidence that they were of the familiar modern triangular shape before some time in the region 800-1000 AD, when lots of illustrations start appearing in Scotland and England, and subsequently in Wales and Ireland. (But the places where the illustrations appear first can not be assumed to be where the instuments appeared first).
   From 1000AD there is a huge amount of good evidence about harpists throughout the British Isles. Alas, we don't know anything whatsoever about the music they played till well into the Middle Ages.
And I still think Tony Blair should get the old guitar out.