It's part of the current 'terrorist' paranoia in the UK, which some people feel is being whipped up by the media and the parts of government whose budget gets increased if there are any terrorists.
Londoners at one time were used to having thousands of bombs a day going off around them. They just used to shrug and get on with it. Now a wisp of vapor is a media event. If someone gets killed by a terrorist bomb these days, people are OK with massive security measures that shut life down to a standstill. Their parents would be gobsmacked by this pathetic attitude to personal safety at all costs. I used to play in the bombsites as a child, the idea that life has to come to a standstill because someone somewhere wants to kill you is ridiculous. It's never happened before in human history; but now we are treated as sheep that need a shepherd 24/7.
This is the modern media-led world where a minor irritation is a huge event - because nothing else is happening anywhere. It's just too darn safe now, and today's generation in most Western countries just don't have a clue how safe and easy life is for them. A sneeze gets headlines.