Danny Pink

 was a teacher at Coal Hill School, where he taught mathematics. He had previously been a soldier, and established the Coal Hill Cadets at the school.

A pupil once asked if he had killed other soldiers to which it's implied he has. The same pupil then asked if he had killed any civilians to which he visibly became distressed, once again suggesting he had.

He was introduced to Clara Oswald by Mr Armitage. She later asked him to join her for a drink and he embarrassed himself. (TV: Into the Dalek)