You also talked about vacant/boarded up stores front, and you Also mentioned local and international Businesses are no longer interested in servicing the UK populous, for which doesn't stimulate growth, however this i cannot ascertain this information, because I don't stay in the UK, so we would need verified information to come into conclusion on that, because there are lots of investors who would gladly want to take their investment to the UK, and I also believe they're are lots of availability of persons who are still job seekers that would want to fill in those vacant positions. For an economy that has Such capital base, trust me, investors won't think twice to make investment hence the opportunity is there.
many websites do retail listings for renting/leasing/buying for towns. so you can see if towns have any/many vacant stores.
it is also worth noting that the UK is a small island, so most international businesses want to aim for countries with larger populous. EG indian/asian businesses expanding into america rather than the UK (go big or go home)
take boba(bubble) tea.. it went from taiwan to america first in the 1990s and expanded through the millennium, the UK didnt get to taste boba tea until 2011
anyway, here is the chicken vs egg problem
when businesses close due to multitude of reasons, retail stores become vacant.. other businesses look at the analytics of visitor numbers and footfall numbers of a town center and if a town does not see enough people visiting the center of town shopping area, a business will not want to lease space and set up shop in that area and usually pick a more popular town to invest in(go big or go home)
some then say its due to(egg chicken) or requires(chicken egg)... more housing so that more people live near the center to then shop in the center. however if there are no large job opportunities in the area people wont want to move to the area.. and so some say its due to or requires more retail stores open in the town center to inspire housing development to get the populous to grow(people dont want to move to towns with nothing to do for work or pleasure)