Well if this is bad because of noscript being required to be safe and the use stopping ads from getting to the eyeballs, how much worse is Phorm replacing mid-stream the adverts the site is expecting to hand off and replacing them with ones BT and Phorm are selling?

If you're not going to get the ads the site needs to keep going no matter what you do, why not ban all ads? No loss to the site, after all: the ads were being blocked by BT.