If you like throwing things at or on people and want a reaction, there is no better place to do this than the Palace of Westminster.
Way back in the mists of time I went out with a guy who was a parliamentary research assistant and we often used to meet at his place of work. Folks who work at Westminster seem to like it so much that they just can't face leaving.
Anyway, ordinary folks, mere tax payers and the like, can get into central lobby, via airport style, pat down security and you get a sticker too. So there I was one time in one of the many eateries, MP spotting - John Prescott - pie and chips - that sort of thing, when it flashed up on the TVs, 'security alert, central lobby.' The TVs btw show what is going on in both houses. Bit like ceefax and about as interesting. A man had thrown what turned out to be flour in central lobby and shouted, 'You've all got anthrax.' Maybe he used capital letters and a few !!!, I don't know, I wasn't there. It was around the time when people were posting stuff in the US. He thought he'd deliver it in person.
Now my reaction to a security alert is to walk away, avoiding windows, crowds and the underground. If I was medically useful, I hope I'd react differently, but I'm not. Walking away was not an option because the entire parliamentary estate was locked down. The bloke I was with then displayed that indeed he did have the mental age of a 10 year old as he thought it would be great to take a look. My Dad displayed that he has the mental age of a grown man and within minutes had texted, 'RU OK?' or the like. Compare and contrast.
The flour man was carted off. We got out after about 45 mins and went to hear William Hague in Millbank, who was very interesting and I no longer hang out in the Palace of Westminster. My Dad is still my Dad.