I've no connection with the AAIB, nor with the individual who's been referred to here, but his CV doesn't look at all like some cartoon Colonel Blimp, but rather a highly qualified and experienced aviator and accident investigator. Of course, if he wasn't such a person he wouldn't have got the job. I do know some present and past British army aviators who certainly aren't the sort of 'military' type of popular imagination. YMMV