... you mention CGCGCD, learnt from Gavin Davenport. I spoke to Chris Wood a few weeks ago, who told me this is the tuning he uses - and he makes it sound fabulous. When I went home to try it I realised that it's basically a cittern tuning with a D on top but, I think, the guitar is easier to manage than a cittern (personally).
Ian, Gavin was teaching a combined guitar, cittern, bouzouki class. For bouzouki, the tuning was either DADA of CGCG (depending on string gauge) and for cittern, CGCGC, so you are right.
Chris Wood, marvellous.
There is a guy called David Delarre who is the guitarist in Mawkin and I think he has been experimenting with this tuning recently. He's made it through to the YFA finals, so you will get a chance to hear him on the BBC R2 folk prog sometime soon.