This Service Riser cavity runs like a chimney through the building

This Service Riser cavity runs like a chimney through the building
By Phil Murphy

It adjoins numerous flats at every level, is not separated at floor levels and is only accessible by entering a dwelling.

The door to it was fifty years old and not fit for purpose, it is a fire door and has smoke seals and an intumescent strip. If you see a closed door such as this and it has three hinges (a requirement for fire doors), you can reliably assert that it should have those protective features mentioned and forms an integral part of a compartment barrier.

Ventilation installed a few years ago lacked fire dampers that respected the compartmentation and in flats where dampers were installed, annual service inspections of the dampers was physically impossible (the inspection facilkity that you can see, with blue handles, is a necessary and recent addition (at every point where the duct passes through compartment walls). They should be checked annually by a qualified engineer regardless of the purpose of the ventilation (BS 9999).
Non-compliance may lead to the spread of smoke, toxic gases and fire that are outside of the building design expectations.