The problem was with my Esperia campaign file. I had a legacy ship in there that's not included in GWX, St Naz or my mod so anyone trying to play after Aug 1941 would suffer a CTD. I didn't find it during Esperia testing as I wasn't using a fresh install but had rolled back to what I thought were the base files. Lazy

. It will probably be a problem with my Esperia add on as well and I hope people backed up their campaign_SCR files as the Readme suggests. The problem will be sorted for the release of this mod.
I'm just glad that I've taken the time to test properly rather than rush the mod out. No deadline!
RM Aquila: