2Planks - not quite, although I must admit it is tempting to goad them into doing away with our current schemes so we could have a good old scrap with Gordon et al.
Anyway, as for pensions being Negotiable Instruments, unless I have misunderstood, that's close but no cigar.
The Armed Forces Pension scheme comes under a bit of pensions law I believe is called Exceptional Pensions Laws, and the rules of the scheme are set out in prerogative instruments. These are not subject to approval, annulment or amendment by Parliament, but instead derive their authority directly from the Queen. In a related bit of legislation, the 1865 Naval and Marine Pay and Pensions Act sets out exactly what constitutes a prerogative instrument. For the RAF, this means QRs. From that, and assuming things haven't changed, then whoever decides on QRs would theoretically have the power to tamper with the pensions. So I'm guessing that would be the CAS, CDS etc in conjunction with Min State for Armed Forces (and prob the PM given the contentious nature of the decision) making a recommendation for Aunty Liz to approve and implement.
If that is so, I guess it would all depend on what was being offered to those at the top of the greasy pole in order to get their buy-in.