Nice! The N&L P&S shoes I've owned who were made by Grenson did not have that sole at all, and like you I've never seen it from them. I'd say Cheaney, they do a lot of rebranded shoes, and I think they look like the soles of the Cheaney Imperial collection, which have the same quite extreme fiddle back. Pic of it here on a pair I owned, if you scroll down a bit: http://imgur.com/a/MxcQw
And we have a winner! They are quite clearly Cheaney made. I wonder if N&L have switched entirely from Grenson to Cheaney for their Poulsen Skone range?
By the way, I check your blog weekly, keep up the good work! Since I live in the vicinity of Borås, it was quite interesting to see your post about my go-to cobbler. Your post about Skomakeri Framåt was also very informative, especially as the samples they show on their homepage are a bit... well, let us just say that I think they left something to be desired.