[Maths-Education] Recent history of textbooks in England?

[Phillip Kent]

Dear colleagues,

I have been trying to track down any articles on the recent history
(say, 1990 onwards) of textbook development in England. 

We have witnessed the rise and pretty much dominance in mathematics of
textbooks tied to examination schemes of particular examination boards
(and I know science is similar, but don't follow other subjects). This
obviously makes good business for publishers, but was this trend ever
questioned by those bodies which oversee education in England? On what
grounds have exam boards and publishers justified this development?

Thanks, Phillip