Staff Sergeant
From Tardis Wiki, the free Doctor Who reference
Annie Frederick (PROSE: Operation London) was a Staff Sergeant under the employ of UNIT, (PROSE: UNIT's New York Operation Expansion, UNIT's Position on The London Incident, Operation London, Operation Mannequin, et al.) though shortly after the crash of an alien craft into the Thames in 2006, she became a captain, (PROSE: Number Ten) and then from then on was demoted to sergeant. (PROSE: Rose Tyler, Guinevere One, Project Rooftop)