Yes I bought the phone outright from Apple. I presume because I bought it outright and only later set up a monthly sim only contract that the phone is unlocked.
In Setting > General > About > Carrier it states my phone companies name (that I have a sim only monthly contract with). I'm not sure what that proves?
Apple UK retail and online stores ONLY sell unlocked iPhones
unless you specifically take a contract and a Carrier contract price through them
not something you can do by accident
It will be unlocked ................
BUT to make sure and whilst you are still in UK
try another carrier sim
Apple stores have been known to accidentally code an unlocked iPhone
as locked at checkout and it would be easily fixed whilst here
not from China