An article by Elizabeth Truss MP in the The Telegraph. Some quotes:

With a lower proportion of students studying the subject in sixth form than any competitor nation, our next generation of maths teachers, city quants and rocket scientists is in danger of extinction. This feeds into all areas. There is a shortage of teachers at primary and secondary levels.[…]

Yet maths graduates are in demand. After medicine and dentistry, it is the highest-earning degree, with maths graduates earning twice that of a non-graduate. Those with a maths A-level have a 10 per cent earning premium. So why aren’t students queuing up to take maths?

One reason is the perverse funding incentives. More is paid to a school with a student getting an A in media studies than one getting a C in further maths. This is nonsense when the value to the student and the economy is considered. Further, A-level media studies, psychology and physics receive a 12 per cent funding premium, ostensibly due to equipment requirements. Consequently, only half of comprehensive sixth forms offer further maths, yet nearly 60 per cent offer media studies. Subjects such as psychology are catching up in popularity with maths, for the same reason.