Evil bob I think you are over stating the case somewhat.
If the Avgas facility meets the CAa requirements - which of course it must then local authority approval is pretty much a 'given'. My local authority 'sells' a licence for quanties over 50,000lts (should be enough!) for £114 per annum.
The insurance issue is interesting = ask your insurer whether as a licensed airfiled you are covered for a major fly-in, the naswer will be somewhat similar to the answer you get from the CAA. The prospect of additional revenue is irrestible. Both the CAA and insurers will state this is an exceptional activity - and so not covered by the usual arrangements. Having been involved in this a couple of times the answer is to categorically stated that whatever artifical criteria they apply will not be exceeded (the CAA number is IIRC 200 movements so expects the insurers to follow suite).
Overall the airfield simply has to pay a little less money, effectively for nothing. Will it change the world? no, but it is a useful improvement.