We have a pile of boxes here from moving house. They're robust double-walled archive boxes that fold flat. (This was the link, but the Staples site appears buggered.) You can fill these things with books with no problems. They stack very nicely too. We have no foreseeable use for them and they're a nuisance and in the way. Please take before we just put them in the recycling. FREE! JUST FETCH! We're in E17. My email is email@example.com. Tell your friends!
(tajasel, some are set aside for you!)