wow thanks for all your responses so quick and helpful.

My DS is a little fella (2.8kg) and has little chicken legs so it could well be an ill fitting nappy. I will definitely try a different brand and triple check his willy wonka is facing south into the most padded part of the nappy.

He definitely isn't overdressed as we have slowly started removing items as that is what we first thought was the problem. He has been sleeping in just a one piece "wondersuit" with no singlet on), he is lightly wrapped and he likes to sleep with his arms out so I'm pretty sure it's not sweat. I've checked his torso (thanks for that tip) and he definitely isn't clammy. He's a healthy looking cherub too so I don't think that he has a fever.

So we'll try a nappy change and see if that makes a difference, the community health nurse is coming for a visit on Friday too (to do his 1-4 week health checkup) so we'll ask her lots of questions about this as well.

Cheers and thanks so much for the support
Wook