Portsmouth's building stock is shaped by its role as a working naval city — dockyard and defence facilities, dense high-rise residential blocks, and a fast-growing commercial and leisure quarter around Gunwharf Quays, all packed into the most densely populated city outside London. Portsmouth City Council alone manages 22 high-rise blocks across the city, and that's before counting the naval base facilities, retail, and office space stretching out toward Havant, Fareham and the wider south-east Hampshire coast.

Every one of these buildings depends on fire and smoke dampers to stop fire and smoke spreading through ventilation ductwork between compartments. A damper that's corroded, obstructed, or never been tested won't close when it's needed, and given how tightly packed the city is, that's usually only discovered during a fire risk assessment, an insurance audit, or worse.