It's a shame if the "liquid bomb" plot people actually went to the trouble of buying the chemicals, since they got 110% of their goal- demonstrating their mastery of us by fear- just by talking.
But assuming they had succeeded, and on one day 10 airplanes had made unscheduled mid ocean landings, what would we do?
I know, panic and cower, just like we have done. And our leaders would go obediently to mosques, to apologise for anger against Moslems that no one has or acts upon, and to explain that as long as one merely sympathises with murderers, one has a free ride. And there would be lots of appeals, weepy services, and the families of the dead would be sad and/or richer.
But I mean, what would we do against the enemy?
The actual plotters would be dead. Assuming we ever found out who on the missing airplanes blew them up- fat chance, unless someone talked- they are British. Their encouragers are British. There is no "proof" that there is any participant in, or financier of, the outrage who is not British.
What do we do? Aside from just take it?
Until we get aggressive with those who encourage murder, that's what we'll have to do. Get used to the idea, presidents and prime ministers. Now and then, you'll have to execute the sad announcement/grovel at mosque/memorial tribute/we are resolved speech/ wait for the next one gavotte. Your masters in Bradford and Dearborn will be in touch.
Don't feel badly about being the puppet of random criminals. I'm sure that Washington and Pitt and Lincoln and Curchill would do exactly the same thing in your place.