Well a whole series of in-depth document reading, no end of checking configurations and reading and rereading post after post of others experiences. It boils down to this.
I had one simple thing missing from my vhosts file. The ServerName attribute!
It just goes to show that when looking for a solution to any challenge start with the first layer. I am posting this just for completeness should any other poor soul find themselves spending 10+ hours down the rabbit hole…
A win is a win though!