If nothing else it makes a difference to the "confidence" of the region and the people living in it.
I have no evidence to support the notion, but I would also guess that it makes a big difference, purely by making the place easier to get to, to tourism, business etc.
I agree entirely. Many years ago I seem to remember here were plans for a Folkestone to Honiton trunk road. Whatever happened to it.
And I am convinced of the importance of infrastructure. We have friends in Alsace who were convinced they missed out for years because Strasbourg didn't have a...
But we already have the M27 south-coast motorway in Southampton. It goes to Portsmouth in one direction and about a third of the way to Bournemouth in the other direction before petering out. Sorting Chichester, Arundel and the back of Worthing/Lancing out would greatly ease my frequent journeys...