No you won't have a chat with the CAA. All that happens with MOR's is they go into the 4 month backlog. And a basic service implies absolutely zero deals without further communication. Which you can either accept or refuse as you wish.
If the controller used another form for breach of the ANO you might get a call to which you reply I was outside controlled airspace tracking along xx feature 1 Nm outside the boundary. As you say the radar isn't as accurate as people might think. I wouldn't like to guess how far you actually have to get inside, as that sort of buggeration behaviour skimming boundarys and cruising 100ft below CAS seems particularly pointless to me if you have room not to.
It would be interesting to know if Solent thought that they were inside as well. It might very well be that the FR's overlay is out or there is some screwup with the mosaic if they are sharing and merging feeds. For chasing that one person may open a whole hornets nest of tech issues which would be a pain in the neck and expensive to get sorted.
Yep take the guy to court if he did bust the zone. But unless they think he will plead guilty or managed to get well inside the zone they won't touch it.