The term coconut when addressed by a black to another black means they have shunned their black heritage and integrated into the white man's culture. This is perceived as a negative slur and confirms exactly what someone in this thread was saying earlier about the lack of integration. The Labour MP was insulting the Chancellor for having integrated into our white culture, into a perceived privileged educational establishment and into a white country. Which speaks volumes about how some blacks see integration as demeaning to their culture, and suggests this Labour MP carries a nasty chip on her shoulder and has decided to make it public. It has close similarities to the phrase "An Uncle Tom".
Uncle Tom
/ʌŋkl ˈtɒm/
noun
offensive•North American
noun:
Uncle Tom; plural noun:
Uncle Toms
- a black man considered to be excessively obedient or servile to white people.
- a person regarded as betraying their cultural or social allegiance.
"he called moderates Uncle Toms"
It's a view she is of course perfectly entitled to have, but one might say that publicly stating it as a black Labour MP at a Labour conference could be considered a somewhat suicidal career move.