Has anybody tested if an iPhone from John Lewis locks to the network of the first SIM used in it?

Posted 29th Mar 2016
There is conflicting information on the Internet that only iPhones from the Apple Store and giffgaff are fully unlocked: i.e you can swap SIMS and networks at will and use UK or foreign SIMS interchangeably. Phones from other suppliers, such as John Lewis, are reported to lock to the first SIM inserted and stay locked.
I want to know if someone has, for example, first inserted a Vodaphone SIM and then an O2 SIM and found that either will work. If you were to put a "3" SIM in first it spoils the experiment as they apparently automatically unlock the phone. I want to buy an iPhone from John Lewis following a hot posting on HUKD and first connect it to giffgaff who use the O2 network, and later on use it in France, Austria and the USA with local PAYG, or borrowed SIM cards. Please try to avoid using the word Android in your reply and thanks, in advance, for any help.
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