Last time I quoted Craig Murray as follows:

There are two possibilities: either they are trying to provoke more "Islamic" violence, or they are very stupid.

Come to think of it, there is a third possibility. They may be trying to provoke more Islamic violence, and be very stupid.

I think it's clear that the one possibility that we can rule out is the second one: it's not pure stupidity. As evidence for that, I would mention two obvious PR events which were staged by and for John Reid: the occasion when he was heckled on camera by "Abu Izzadeen" and the occasion when he "took charge" following the publicity surrounding the absurd "liquid bomb plot".

See also:
http://disruptive.org.uk/2006/08/28/airport_security.html
http://disruptive.org.uk/2006/09/18/airport_security_2.html.