FWIW, I'm a US 10E in the AE 5 last and I wear a UK 9E in all my UK sized C&Js. I don't have any AE 5 last shoes anymore, but at one point I think I measured and a UK 9E in the 348 last was actually a bit wider than a US 10E on the AE 5. No experience with Paraboot. I would guess a UK 6E would fit you in the Northcote.
12/20/14 at 8:20am