Interesting to see the call for a new 'northern assembly' to help tackle the north-south divide, partly inspired by the observation that the recession appears to be increasing that divide.
Here's my blog post from a couple of months ago talking about why the divide is increasing. In short, a lot of it is to do with the fact that the lower skilled workers are getting hit hard everywhere. The north has a higher proportion of lower skilled workers, so it's getting hit harder than the south. But lower skilled workers in the south are doing pretty (equally?) badly too.
Against this backdrop, would decentralisation in the form of an elected northern assembly help? As I have said before, there's precious little evidence to back up this assertion. If you are interested in reading further, Max Nathan discussed some of this a couple of weeks ago in a post on city deals (and you can find more details on the evidence in this older policy piece).