I got this link from the Times Election 2005 weblog. If you visit this part of the Channel 4 website you can watch some spoof Party Political Broadcast adverts that have been created by a very talented advertising team. In one of them for example:
"An old man lies in obvious distress on the floor. Two canvassers approach him, one Labour, one Tory. Instead of helping him they begin to argue amongst themselves before a yellow-clad Lib Dem superhero saves the day."
So you can see the tone of these adverts. Well worth a watch.