I've got two ideas I'm circling:
The People's Republic of .EXE-A Cold War era AI that bloomed in the Maunsell Sea Forts and now serves as a reluctant information broker in return for being allowed to live.
https://en.wikipedia.org/wiki/Maunsell_Forts
I'm also looking at something involving Manod Mawr, the Welsh mine where the National Gallery's stock was hidden during World War II. Which in the game world would be an active cultural 'seed vault' and somewhere the Company is very eager to get into.
https://www.nationalgallery.org.uk/about-us/press-and-media/press-releases/manod...
Also have half ideas about Dinorwig Power Station ('So what's in the Turbine Hall?' 'Excalibur.' '...WHAT?!')
https://www.electricmountain.co.uk/Dinorwig-Power-Station
And possibly a version of the Strategic Steam Reserve which is basically a free-floating, on rails nation inside a nation.