Ron Fenest
I fear you were led up the garden path. There never was a conditional offer to be able to reconsider transfer to AFPS05 at alater date after Apr 06. The only way you can "transfer" now is to retire from service, and then rejoin later, in which case you would rejoin into AFPS 05. That doesn't mean you would suddenly achieve all the benefits as though you had transfered whilst in continuous service.
There was a condition, which is still active, for RAF personnel selected for redundancy under the current draw down, to leave by Apr 08, that if they had previously transfered to AFPS 05 but could now show that their redundacy terms would have been more advantageous had they remained within AFPS 75, then they could elect to revert to AFPS 75 to exit the Service. I am not aware of any other such arrangement, although it is possible that there are others.
Legally, I don't think PAS/PES(A) membership is a "Term of Service", any more than entitlement to various pay rates and types of allowances could be seen as such. "Terms of Service" are now laid down by Statutory Instruments, and are generally limited to the types of engagements available, the relevant qualifying start and end dates, rights to end service under various circumstances, transfer to the Reserve etc.
Regards
Ginseng