"You mentioned "European Megalithia". Did you mean just the study generally or were you referrring to something more specific - like a website???"
Just the study in general, but this site will have to go Europe wide with the coming of The Megalithic European by one Julian Cope.
I have recently added bits to megalithomania that expand it's area of coverage into the UK as far as the cross-over areas go. I'm not doing the same thing (i.e. a page per site), but am putting up essay/discussion/weblog type pages on this. The Clyde cairns (once Clyde-Carlingford?) are detailed in the introduction to Estyn Evans' great book <i>Prehistoric and Early Christian Ireland - A Guide</i>. Published in the 50s it's well out of date on most things, but seems to form a very big significance between the Clyde & Irish CTs. As Evans excavated or identified over 100 court tombs, which were formerly considered a rarity here, he knew what he was talking about.
With Evans the Clyde-Carlingford culture theories seem to have been corrected to include the north of Ireland too. Evans seems to prefer a spread from Scotland across Ireland with the tombs getting more elaborate. A lot of others go for the West-East and getting worse theory, as is now known to be the case with pasage tombs.
Yes, the Clyde-Carlingford cairns are something I will have to get my head around at sometime. Perhaps after the portal tomb study is complete ...