For example; say 5 grade two boxes close, the boxes are resignalled and made 1 grade six in a new location. The grade 2 men must apply for the new grade 6 job because of the fact that you cannot gain promotion out of your signal box closing. But the grade 2's could be moved to another grade 2 or lower location, just not anything higher than a 2 (unless they apply).
If you are in a higher grade PSB lets say a grade 7 for example;
The PSB men will as a general rule move with the job when resignalled, unless of course the new job was up graded to say, grade 8, then the grade 7s would have to apply for the 8, or move to lower grade jobs 7 and downwards.
A good PSB example at the moment would probably be TRENT and LEICESTER where by the jobs have more or less just moved like for like but to a different location, the EMCC, i dont beleive any redundancies have come from either, and of course a few will have chose to go early, or elsewhere.