To support Ken, I was posted to a holding post for the Nimrod AEW3. It was unlikely that I would remain at my post for more than a year or so so Dau no 1who was approaching her 11+ and had moved from Scotland and therefore not likely to get a grammar school place was put in to a boarding school. Dau 2 followed a year later.
Then the Nimrod was cancelled and I was posted but as it happens it was in commuting distance - 114 miles per day. We stayed put and continued to get CEA for Dau 1. Dau 2 however won a place at the age of 13 to the local grammar and we ceased claiming CEA for her. We took a calculated risk that I would not be posted to 'Vegas' or some other highly desirable location. Dau 1 however continued to benefit from CEA as she had started her A-level course.
My commute posting could have been to somewhere else entirely such as Lyneham and we would have moved benefited from the CEA.
There really are many permutations. I mentioned above the possibility of screening postings for the education stage. What would happen is P-staff said that a posting was not probable and then you got a posting?