Brilliant - now very rare and thankfully, not graffittied over. There was a great EWS sign on Brixton Hill - until the owner deliberately painted over it with a graffiti-type mural.
I don't know how common it was but in Coventry and Birmingham the canal was used for Emergency Water Supply. Yellow Circles were painted on the canal bridges to help identification in the blackout and holes where knocked in the brickwork to allow hoses to be dropped through into the canal. These holes were filled with a temporary door arrangement and, although re-bricked after the war, are still visible on a number of bridges. New Inn Bridge, Foleshill, Coventry And from the canal towpath the same bridge This bridge has just the remains of one door but the yellow painted circles are still in evidence. Another example that shows door remains but a different type of painted indicator And this example from Birmingham retains the doors - although almost certainly replacements (Apologies for the length! Despite having gone past these thousands of times I've only just had them pointed out and got a bit obsessed - as you do)
Seen these in Nottingham too. Wonder why they went to the trouble of building these access holes when they could just drape the hoses over the top of the bridge's parapet??!
I did wonder that too....thought it might be because the hose would kink more going over the parapet rather than through the hole and straight down ?
‘Emergency Water Storage Tank’, Charles Ginner, 1942 | Tate Charles Ginner Emergency Water Storage Tank 1942 Photo © Tate CC-BY-NC-ND 3.0 (Unported)