Police search maze of military tunnels near family garage of Sarah Everard murder suspect
https://www.dailymail.co.uk/news/article-9354459/Police-search-military-tunnels-near-family-garage-Sarah-Everard-murder-suspect-cop.html
Way back there were reports that tunnels linked the northern tube line was being used for nefarious purposes.
I know there are a number of WW2 bunkers sited along the northern line.
iirc there were youtoob videos of people exploring them.
Policeman linked to diplomatic and nuclear protection units. Very spoopy.