If British authorities want to send people onto planes carrying nothing but their wallets and identification for the next week or so, that is reasonable. No one begrudges them a momentary anxiety about whether they successfully halted the plot.
If British or American authorities want to ban all liquids from airplanes, that might be reasonable as well, as long as the airlines are willing to step up and find ways to readily supply passengers with sufficient amounts of water as often they need it. There’s a reason why everyone in coach carries on a bottle of water these days.
If British or American authorities want to ban all carry-on luggage in perpetuity, preventing passengers from using laptops, iPods, portable DVDs or other electronic devices, as well as preventing them from reading books, writing on legal pads, coloring or drawing, and so on, then I’m pretty well done with flying to any destination over three hours away unless it’s an absolute and dire necessity. I especially draw the line at preventing people from carrying books on board.