The MoD have a responsibility to provide a safe operating environment (ie. Govt Airfield) and the Association/Club have responsibility under the GAI to provide a safe club environment which complies with all the regulations (mil and civ). The airworthiness is the responsibility of the aircraft operator and is regulated by the CAA for all "Group A" aircraft (yes, I know Group A no longer exists for the purists!). So there is no Duty Holder responsibility/construct for the operation of civil registered aircraft for non-publically funded service flying club activity. Airworthiness is CAA business.
However, if publically funded, like civvy regsitered Grobs, Fireflys, gliders, etc... Then there is a Duty Holder in 22 Gp with an ensurance/assurance process - I believe this to be OC 3FTS? Airworthiness in this instance is MoD business but uses CAA regulations.
So the difference comes with "publically funded" and "non-publically funded" flying activity.
Make sense?
CPL Clott