Mil can be forced to take block leave, CS can't (different T&C), and plenty of us don't want to have to take a full 2-3 weeks off over xmas, and instead use leave at a different time.
Jim, agree with your sentiments but enforced block leave is, or was, very common. Typically, 2 weeks in summer and 1 at Xmas.
Also, in my first staff job in London, my T&Cs stated I was not permitted to take leave for 2 months following publication of the Main Assumptions; that is, roughly mid Feb - mid Apr. Also, for 2 weeks when the Alternative Assumptions were issued in the Autumn. You will appreciate both periods were variable, so you couldn't book holidays in advance. No TOIL or OT, but in return MoD allowed a certain flexibility; for example, you were allowed to wander off during the day to sign on for Family Income Supplement.
