When the Gender Recognition Act was passed in 2004, Parliament was assured by experts that only about 5000 people in the UK would qualify to get a Gender Recognition Certificate. When a few MPs and Lords attempted to point out obvious problems that would follow from making it possible to get your birth certificate reissued with the wrong sex on it they were told it didn't matter because the number of people it would affect was tiny. Well:
(a) it wasn't, because each of those people with a GRC goes out into the world and interacts with others, so the numbers affected are far higher than 5000
(b) in the end most trans-identified individuals have not bothered to apply for a GRC, so the legislation is now largely irrelevant - but
(c) the arrival of the internet, easy access to porn, social media and so on have led to a social contagion which has led a lot of troubled people to identify as trans or non-binary in the hope that it will solve all their problems, and has given a glorious opportunity to many fetishists (all male) to claim to be part of this persecuted minority and to ride roughshod over women's rights and safeguarding procedures introduced to protect children and other vulnerable groups.
Throughout this mad period, many people who really should know better have refused to look at the facts and are still behaving as if the numbers involved are that original 5000 with a diagnosis of gender dysphoria. That's the only way I can explain this Civil Service policy - that it was drafted and approved by people who thought only a tiny handful of staff would be in a position to take advantage of it.
Of course, anyone attempting to point out the reality of the position has probably been disciplined and faced the possibility of being sidelined, demoted or sacked as a hateful bigot, so I imagine most Civil Servants have rolled their eyes and kept stum.