While at High Wycome, I took the opportunity to take photos of the fire escapes decorating the outside of the warehouses. These are essential details for models, but are frequently missed off, partly through lack of pictures to follow.
I'd assume that these aren't originals, or at least very well preserved if they are. Climbing up a set of steps, everything seems solid, apart from where the steel has been replaced by checker plate.
Everything seemed to be a standard design, leading me to suspect wholesale replacement at some point on all the buildings. Modelling this stuff isn't quite as easy as you might thing. There are quite a lot of joints with balls around them. A blob of solder, plastic bead or even blob of PVA might do the job for these. Or just ignore them, the main thing being to get the stairs, handrails and supports in place.