Require all secondary teachers to pass the same exams their students sit

I want to make all GCSE and A-level teachers pass the same exams as their students in exam conditions to ensure they have the relevant knowledge in their subject to teach it well and to reduce hypocrisy in the education system.
We believe teachers who do not know their subject well enough to get a good grade in the same exams they expect their students to sit should not be teaching the subject. We think this will ensure all teachers have up to date knowledge of their subjects.