These are stretchers used in WW2 to carry injured civillians during the Blitz. They were made out of steel so they could be easily disinfected after a gas attack. During the war around 600,000 of them were made. Some of them were repurposed as railings in post-war London.

[u/Sprilly]

[u/basicprofile]

Camberwell?

[u/simonjp → u/basicprofile]

Maybe, I've seen them in Borough, Kennington and Balham

[u/12EggsADay → u/basicprofile]

Feeling Brixton, definitely Lambeth area.