Based on James McClean's recent tweet about the issue, it's very clear where the Republic of Ireland winger stands on calling his home city Derry rather than the version with the London prefix.  

And given his allegiance at international level, it is also clear that the player identifies with the Republic of Ireland rather than the North.

However, in action with his club West Brom tonight against Manchester City, Sky Sports' commentator Alan Parry disregarded that in his description of the player as a "Northern Irishman from Londonderry":

The NI Man from Londonderry?? More fuel on the fire? James McClean Rep Ireland player from Derry @SkySportsNewsHQ pic.twitter.com/iiRQ7Hwp79

— Ryan Stewart (@ryanmtstewart) August 10, 2015