Took a punt with this phone because it's purchased as T-Mobile PAYG.
Received yesterday and can report that mine was unbranded (no network branding on case or screen) and unlocked, with the PAYG pack bundled alongside in the parcel. Put my Orange sim card in and works like a dream!
Love this phone already. Fantastic screen and very fast and fluid operating.
Seems like a bargain - Amazon and Play £439.99.