... that conclusively states these are 'Pole Mounted Enclosures' for FTTP Brownfield.
so we just need to figure what it is enclosing
As FTTP is not my 'game', I'm guessing just a simple fibre joint ?? Here's a list of pole-mounted fibre gear ......
Pole Mounted Fibre
Distribution Point (12 end users) Distributes 12 fibres to 12 end users via blown fibre bundle.
Pole Mounted Fibre Distribution Point (32 end users) Distributes 32 fibres to 32 end users via blown fibre bundle.
Pole Mounted Primary Splitter Node (32-way dual split network) Provides 1st level of split on 32-way dual split network.
Pole Mounted Splitter Provides 2nd level of split on a dual split network.
Pole Mounted Transition Provides joint between underground and overhead
Blown Fibre Drop Tube ManifoldDistributes up to 12 single drop tubes from one 7-tube or 12-tube Blown Fibre cable