If you want to get a nuclear-powered submarine refitted, repaired or refuelled in Britain, there is only one place to go – Devonport dockyard in Plymouth, the biggest naval base in Western Europe.

Running across more than six kilometres of waterfront, the dockyard has been part of the landscape for generations. It dominates the western edge of the South West England city, encased by high fenced walls, security cameras and warning signs about police dogs and potential arrest for ‘unauthorized activity’.