No, no, Beagle. We can find some rockets to use, I don't think that's the problem. You can't put a SAM ring around London because all the traffic would have to enter it to get to Heathrow.
But it's OK, what we do is this. Let all the aircraft enter London's airspace because they're behaving normally and heading for LHR. Then, when they suddenly deviate from their approach and head towards the Olympic arena we engage them with Rapier so that they lose control and the burning wreckage lands in middle of the City. So we save the stadium at the expense of three crowded blocks nearer the centre of London.
I guess the choice is the athletes or the bankers. Hmm. Maybe I won't go there!!