"The question is, should schools insist on teaching music according to the National Curriculum, or should they show some sensitivity and flexibility where parents object on religious grounds?"

I think that there need to be some basic but VERY FIRM guidelines about what kind of 'flexibility' a school can indulge on behalf of any specialist group. As said previously, what we need to prioritise first and foremost is children's rights and welfare, and ensure that schools are not granted so much 'flexibility' that they can basically get away with willfully ignoring genuine cases of what effectively constitute culturally sanctioned child abuse.

My trouble with this case in partiular, is not that religious parents are removing children from music class, but that school boards simply are too spineless to openly deal with any such issues involving other cultures. And instead prefer to 'turn a blind eye' because quite simply, it causes them less hassle.

This amounts to an abandonment of their obligations to the children that they are responsible for.