Azizi nailed it for me.

The term 'world music' is, very simply, a racist British referent to music that isn't white and theirs.

Her high & mighty countess proves that it isn't 'just a marketing term' when she decrees that bluegrass can't be shelved with 'world' music.

It is also a totally irrelevant term outside the UK. The rest of the world has no problem with 'marketing terms' such as Irish traditional or Korean jazz or newgrass.

Apparently, the rest of the music world isn't as stupid as British music consumers who can't find their way round a music store to find their album, without reading some daft magazine first.