I suspect some (not all) of the problem with the achievement of white working class boys lies with white working class men.
I know of families round here where the fathers never ever attend an event at the boys' primary or secondary schools. No parents' evenings. No sports days. They do not read to their boys. They do not listen to them read. They regard school and the family's relationship to it as their wives'/partners' 'work'. They think it's acceptable to take their sons out of school to spend a day on the X-box. We are friends with a family where the boys' success in getting good apprenticeships in sought-after companies is entirely down to the mother's efforts over 14 years and despite the lack of interest from the father.
Perhaps, for the reasons Math gives in relation to Northern Ireland (thanks for that--very interesting), this will change as fathers realise that jobs in apprenticeships or in the local car works are now very rare and precious things and more educational qualifications are essential.