Charlie Stripp of the NCETM (National Centre for Excellence in the Teaching of Mathematics) has made some suggestions for improving maths GCSE given the exceptionally low grade boundaries for the higher paper leading to teachers 'gaming the system' by training pupils to spot questions rather than developing their maths ability.
He has suggested switching to a 3 paper system. The lowest paper (let's call it Foundation) would go up to grade 4. The middle paper (let's call it Intermediate) would test grades 4-6 and the higher paper (Higher) would focus on grades 7-9 and really stretch the most able.
The difference between this suggestion and the old three tiers (except being able to get a pass on Foundation which used to go up to a D under three tiers) is that all students would sit 2 out of the three papers. This would make it far easier to set grade boundaries for 4/5, they wouldn't be so ridiculously low, and everyone would get at least one paper where they could really show what they know.
He also recommends a slimmed-down GCSE for resitters which really focuses on what they need to know.
www.tes.com/news/school-news/breaking-news/exclusive-maths-chief-calls-new-slimline-resit-only-gcse
It's worth knowing that the NCETM is entirely funded by the DfE. One can only hope that they listen to him, but that would require them admitting that the new GCSE has been a complete balls-up and they are not very good at that. The TES story includes the obligatory bland DfE quote at the end that everything is fine really.