gzt: The original UK article I think has the same paragraph. In context of local thinking and knowledge I think it makes sense. Properties were originally evacuated when the area was bombed in 1940something. It was not defused because it was not marked or was overlooked for defusing or in the too hard basket and left alone and forgotten.

One case where editing would have helped. That paragraph makes little sense without local background knowledge.

https://www.shropshirestar.com/news/uk-news/2024/02/23/what-will-happen-to-the-plymouth-bomb-and-why-has-it-only-been-found-now/

Well not really. An evacuation and/or being overlooked for defusing etc might explain why the bomb wasn’t found earlier - but it’s not a “reason that the bomb did not explode” which is what that sentence says.