Leon, thank you for publicising my catch phrase. No charges levied and all are welcome to use it to spread the word!
As tuc wisely says, best we stick to aviation without straying into yet other worlds such as those of the BMA or the Law Society. The main difference between the DfT and the MOD is that whereas the former is not an operator of any substance, the latter most certainly is via its Service subsidiaries. Thus the CAA can and does require every operator to conform to whatever it deems necessary, witness the extensive and costly list of kit and training following the 737 fire tragedy at Manchester. In contrast the MAA can't even accept that the chalice it was handed on its formation was a poisoned one, in that UK Military Airworthiness had been dealt a savage blow by the MOD in the "Golden Period" from which it is still reeling. Before it can begin to put it right it has to face up to that truth. Before it can do that it has to be free of the RAF High Command's continuing cover up of the actions of its VSOs in that Golden Period. To do that it has to be independent of the MOD. Ditto all of the above for the MilAAIB.
As to cost, the poor suffering British Taxpayer will have to bear it. He/she always does. As to the arrangements, keep it simple and sister the MAA with the CAA, likewise the MilAAIB with the AAIB. Both must be civilian led, both can be staffed by military personnel, preferably in new branches created for the purpose, as well as civilians. Expensive? Yes. Difficult? Certainly. But less expensive than the dysfunctional morass that we have today. There is a limit to how many fleets we can afford to ground or even pause. The rest must stay flying and the chronic and systemic unairworthiness purged from them. It will be a long job, hence the sooner we get started the better. Rather that than yet more heart breaking Airworthiness Related Fatal Air Accident threads started in this forum.
PS Apologies for the delay in posting. Mothers Day at Chug Towers!