Why postcode pay doesn't add up

The TUC 'Payfair' campaign has produced a great infographic showing why regional pay is unfair, bad for the economy, isn't backed up by the evidence, isn't what the private sector does, would be impractical and is unpopular.
http://www.tuc.org.uk/images/Industrial/
Pay_Fair_Infographic_2012_1000x3443px_
AW.jpg
http://www.tuc.org.uk/industrial/tuc-21728-f0.cfm