"reduce dependency on external expertise"
In order to do that they need internal expertise. Back in my day in the Civil Service the general service grades were paid more - i.e. if you didn't need specialist qualifications to do your do you got paid more. This "worked" because, back then, HMG was the largest employer of the scientific specialists - combine that with a bit of over-production of scientists at the universities and they could set the rates. There was a bit of a panic when they found they had to pay more to recruit for engineering posts. Needless to say it was the general service grades who ran this system.
I doubt very much that things have changed. Now, instead of rasing pay rates where skills are in short supply they can engage consultants. It's not going to come out of the salary budget to the general service grades can still reward themselves for irrelevant arts degrees.