Anybody assuming the iPhones bought from Carphone Warehouse as SIM Free may be in for a surprise. I found this handy tidbit hidden away at the bottom of the page:
http://www.carphonewarehouse.com/mobiles/iphone-5?intcmp=HP_iPh5
"iPhone will lock itself to the network of the first SIM card that is used in the phone. Subsequently attempting to use it on any other network, for example by replacing the SIM card, may mean it becomes permanently unusable. SIM free iPhones can only be used with a UK-network SIM card, and will not accept foreign SIM cards."
I shall be calling up and cancelling my order. Talk about mis-selling!