The slow death of MilSAR goes back over twenty years. At least to 1998 and the formation of JHC. Was it AVM Niven's idea not to include it or was it policy? Then came the 2001 Provision and Coverage report by the Coastguard. All before 'Iraq 3' and 'Afghan 4'. The idea of unified service was around 20 years ago but clearly from the form of the failed SARH25 we can tell that the idea of a unified all-civilian service was not fully formed until well into the last decade. Defending the British people still included wide aspects of keeping them safe.
I remember H-60 Hawk being the item of choice in certain crewrooms some time back. Perhaps driven by USCG exchanges and visits from Pavehawks. That would never have happened. I suspect you may well have got AW149/189.
£1.6bn is the fixed cost. With the variables, the projected total would have been around £1.88bn although oil price and other changes since 2015 may have modified that. The financial structure is designed to avoid any incentive to deploy or not deploy in order to keep life-saving decisions out of the hands of the bean counters. The training load for a civilian contractor is very significant and it would be pretty difficult to separate those cost in a military context.