I hate british gas, they become increasingly rubbish as greed gets ever more important than service. The engineers that call at the house seem mostly decent chaps though.
couldn't have put it better myself and i speak as on of these "decent chaps"
BG are , like most big companies, greedy and aggressive in the market and as an employer
however they have one saving grace which is a highly skilled conscientious workforce of installers and service engineers so while i cant and wont defend BG business practice i still think they provide quality service
back to the OP depends where he was waving his magnet
radiators are magnetic anyway so that is bogus
copper pipes arent unless theres corrosion/ sludge but even then its not always conclusive proof