This is a galvanised steel staircase for the outside of a house in Donne Place, Kensington, London.
The stringers (side tread supports) are made from 200mmx 10mm flat section steel and with cast iron treads.
The handrail was manufactured from 40mm convex top section and has 40mm x 40mm box posts.
The vertical bars are constructed from 16mm x 16mm square section with 100mm centres.
The landing is made from a galvanised frame, with flooring in cast iron to match stair treads.
The trap-door was fitted in the landing for access to a gas pipe.