I remember reading something which said that, at the start of the 20th century, Civil Service was was a handsomely paid profession and there was heavy competition to obtain posts. However, it steadily fell behind, as the century rolled on until they actually struggled to recruit applicants.
Recruitment and retention problems have been cited as the reason why a non-contributory pension scheme (the old one) was put in place. If the salaries were 13.5% *lower* on a grade-for-grade basis than private sector then they would be on par with each other. (But who would pump that much of their salary into a pension, in their 20s, I wonder?)
In actuality, instead of being 13.5% lower, they were only marginally lower (at least colleagues I spoke to always believed they could get higher pay outside public sector but never made allowances for the fact that the pension subs would leave them with lower take home pay).