I was atending a session here on Denmark in 2008 and Stefan was there too. At that time he was playing D !
Whatever he was playing then. Geoff just shot me an e-mail to say Stefan’s is a 3/4 C.
It’s been some years since I’ve seen Stefan with his pipes at the Swedish Korrö folk festival in the early 1990’s, and then he was playing a D set, so it’s possible he has a D set by another maker then. I’ve never seen his Woof C set. Stefan was in Miltown some years ago I remember and there he had a D set so I’ve always assumed he had a Woof D set. That’s interesting that he has a C set as I have I C chanter, we could have some tunes 
Theres that weird bottom hand finger positions again, just looks unnatural .
RORY