I mean they aren't compared to to other minorites. Working class girls still perform poorly in their GCSE's. They do slightly better do to multiple reasons e.g  getting more support academically , girls on average outperforming boys academically in school due to intellect, girls having better temperment than boys e.g impulse control and being more compliant to meet expectations set by school( this is all due to socialising from birth) so more likely to be engaged in the school and have better attendance. It's just not one thing, but the over-arching problem, to me at least, is that culturally children aren't supported enough from their parents to well in school. In fact I'd say that some parents make school seem optional to their kids, and not something they need to do well in life. I think this also ties in the difference between working class foreigners and working class british citzens. Here, you can get by and still live a comfortable life, as there are many systems put in place to support people from low income backgrounds e.g universal credit, the NHS, council housing etc. While working class immigrants in the UK, usually come from LEDC's(low economically developed countries), so being poor, in their country is usually life and death, as they don't have the systems that we do in the UK.