The H.O. don't demand anything from air ops. They 'suggest' and it's not really a heavy suggestion either! ACPO make the big decisions. It is these guys when they get together who decide what to go for next.
Except for one thing: they don't know what they want next (Met excepted).
No-one is advising them what's going to happen over the next 10+yrs, they haven't a clue, so nothing strategic happens.
Believe it or not, it is the humble UEO who can manipulate movement in the ivory towers. If he/she has their ear, things get done.
The changes that have happened over the 13 yrs I have witnessed have come about by a handful of very passionate UEO's and their unrelenting determination to push forward all sorts of progressive ideas. Of course you need a symapthetic ACPO to run with them too
I think I can safely say that UK police air ops are the most advanced in the world.