Dealing effectively with hecklers can make a speaker look good. I suspect that, from the point of view of the New Labour machine, it's seen as advisable to limit the oppportunities for people who aren't Tony Blair to look good. So a zero tolerance policy towards hecklers is logical. Incompetantly organised on this occasion.

In the past there has been a tradition, both in politics and in other branches of show business, of having the occasional scripted heckler planted in the audience, to allow the speakers who aren't that good on their feet to come back more effectively. Another lost tradition, so far as politics is concerned anyway.