I agree that knife crime rate is high in UK. But in comparison to other european countries UK is least racist. I don't know what kind of racism you guys faced in Plumstead. But I am still living in Plumstead and all I know is when me and my friends see white British white people shopping in this area, we start to talk about those people coz we can hardly see British white people in this area! Is that racism? May be...
-When you go to african-british community area, black people start to peer on Asian people.
-When black people go to Asian community area like Plumstead, Nepalese start to peer.
-When Black or Asian people go to countryside (remote villages), white people don't even want to look   your face.
I think these phenomenon are natural. It's not racism. Even in Nepal, Newar community in kathmandu hate Bahun and chhetri who rule Nepal but we never say it's racism!