Who is a 'Nigerian' Artist?

This on the left is a page from the OM (Observer Magazine) of last week whose cover profile was Kele Okereke, a musician born in England to Nigerian parents.

You can't get a more unlikely black musician than this, playing as the only non-white member in what in England they call an Indie band (I can't claim to know one piece of music by this band, and that's saying something) and of an indeterminate sexuality. This last bit (the sexuality, that is) has raised a bit of an interest among some bloggers. The ensuing mini-debate (involving myself, Sokari & Kym Platt) led to a consideration - not about sexuality - but about identity. To put it another way: who is a 'Nigerian Artist' really?