There is nothing to disagree with here, but its not the end of the story!
Investment in London and the South East is nothing new and has been building for centuries, but the rate of London/SE gobbling up investment and new areas of possible employment has taken off significantly since the UK's membership of the EU, helping to deprive the rest of the country of the investment it needs, mainly because of geography! Of course there have been half hearted attempts to 'off set' this, the latest wheeze is the 'Northern Powerhouse'. Yes of course the cotton industry died out years ago, I mentioned it specifically as a point in time when the UK government should have been seeking to address this loss, not by subsidies but by incentives and investment. There was plenty of warnings and time to plan ahead, but neither 'colour' of UK Government did (for the reasons I mentioned previously) to any large degree. It is true that some areas as you mentioned in Sunderland and Swindon were helped by foreign investment, but large enticements had to be given to attract such investment and this was eventually undermined by EU regulations and edicts. Our Governments, successive governments of whichever persuasion have not sought to, for example, set up a National Investment Bank (que Jeremy Corbyn), they have left it to the 'markets' and to the overview and control of the EU, with its 'structural funding', which except for the odd success, have in the UK as a whole failed. This was mainly because the funding was insufficient, did not last long enough, or was a complete shambles of planning to start with and totally inappropriate to the natural resources (or lack of them) in these areas.
What I am trying to convey is that for many millions of people in the UK being in the EU has made no significant difference to their personal view of the world and where they fit in, its at best been seen as confusing and when it was ruling on things like straight bananas etc. seen as downright foolish, at the level of 'fiddling whilst Rome burned', or 'rearranging the decks chairs on the titanic' etc. For these millions of people the interactive aspects of the EU operations, trade, politics etc. is something they don't trust. The sheer irony of sending so many anti-EU candidates back to the EU Parliament is an example of this mistrust. For these millions the EU is at best a nonentity in their lives, at worst an interfering nonentity that cost them money! Hence the vote in 2016