Interestingly, from April, all Civil Service 1* posts that are being recruited for will be open to external recruitment. Given at this level its as much about management and business skills as it is technical knowledge, could a reasonable argument be made that mil 1* posts outside of direct operational areas be subject to the same requirement?
I think there is a deeply compelling case for reform to the wider military HR system, which is one of the only areas left where you can only enter at the bottom and work up, without any real sense of being able to bring good talent in at the right point.