"Not trying to say that those lucky enough to be picked up did not deserve it, but why so many Flying Branch promotions in the current climate of fleet reductions, planned scaling down of HQs etc?"
Depends on the age of the branch and their manpower plot - it could be that there are a number of retirements etc which need to be covered this year.
I know that another service is aware that even though its manpower is falling, in a couple of years time it will have to do a bumper promotion board at one level to replace the manpower who are retiring, and whose posts were continuing post SDSR. Ironic isnt it - smaller service = more promotion :-)