Letters. Painted on shop shutters in the east end of London. Apparently they’re by a graffiti artist called Eine. I found 10 in one night and then wondered whether all 26 were available. Comments on the pictures helped me to locate more. I found another 16 the next day, but 3 of them repeated letters I’d already found… so I was still 3 short of a full alphabet.
Link to FlickrSet