I spotted it in the first half, it was hovering over the CB stand, pretty high, just assumed it was City or media flying it, disappeared from view after a couple of minutes. I did think if someone wanted to do something bad, this would be quite a clever idea, and before anyone has really given it enough thought.
I suspect (hope) now its happened at high profile games, the security people will be on to it and watching out for it at big gatherings pf people. I wasn't aware you needed a licence to fly one of these, I guess it must be over a certain altitude. Around a football stadium there are often police helicopters, and one of these mixing with a helicopter near a big crowd could get very messy, I know there wasn't one this weekend but that's not the point, and the person flying it wouldn't necessarily have known.