Bicycle Tag of bike

I think BQ's tag is evidence that clues often sound more obvious to the person giving them than to the people reading them. N-Dubz? From Camden?

I didn't get that clue, either, perhaps BQ meant that their 'music' is somewhat like edge ware, but I wasn't about to try and find out.

I think the main reasons why this was a difficult tag was the way the picture was taken, as nothing useful came up with image search, and my aforementioned issue with the way it made the building appear, but that's a lesson learnt for me. Other than that, it was pretty clear from the clues, including the 1940 in the picture, that it was some kind of wartime installation and that there was an underground component to it. Then it was a bit of slogging through web-sites about that sort of thing, and there are only a few that come up easily when searching, so that made it a bit tricky. Good tag, though.