The Metropolitan Police released photos yesterday of some of additional "tools" used in the recent terror attacks on London Bridge. Surprisingly, they included plastic water bottles.
I'm assuming the bottles looked in better shape prior to the attack, and upon closer examination in an environment in which no one's safety is a concern, the lack of visible wires makes the devices look suspiciously fake. Even after the attackers were "neutralized", the bottles would still need to be considered a serious bomb threat until decided otherwise which leads to more concerns for authorities even after an event looks to be over. I don't know if this is the first time "duct-taped-water-bottles-as-real-looking explosive devices has been used, but I would expect to see more of them in future attacks around the world (a statement that saddens me to write).
All of this really emphasizes that "the belts made the bravery of those who took on the attackers even more remarkable".