This thread is properly scary. The very way people have run screaming from even the suggestion that there might be implicit biases showing on MN is indicative in itself.
Racism doesn't have to be people using racist slurs.
Racism doesn't have to be in the Daily Mail.
Racism doesn't have to be UKIP or the BNP.
Racism can be, and more often is, implicit biases you don't even know you have. Taking more of a dislike to someone of colour than you otherwise would, or thinking of people as taking too much space. You don't even know you're doing it. Asking the OP for quotes of people saying a racist insult are missing the point.
We see these biases at work again and again:
Women of colour being ignored (yes, this happens to all women, but even more to WOC) in healthcare.
Implicit bias against black children.
Black girls seen as more sexual and 'less innocent' than than white girls.
And people who are ignoring race, saying they 'don't see colour' are part of the problem. You do see colour, whether you realise it or not, and ignoring it means you're ignoring the problem. Ignoring your biases because you're a nice liberal who's not a racist like those horrible neo-Nazis is part of the problem. Shouting down anyone who even raises it as 'professionally offended', 'goady' or trolling is part of the problem. You can have black friends and be part of the problem. You can have black kids and be part of the problem. If you internalise the messages you've received from birth, then you can be black and be part of the problem.
You might disagree that there is implicit racism on Mumsnet, but, frankly this thread has convinced me of it more than anything else I've seen. @Ghanagirl - hope I've not trod on your toes.