I was just about to say the same thing - usually it's the officers who are clueless, thinking that a year at RMA Sandhurst means they know more than a battle-hardened Sergeant or Sergeant-Major.

In any army in the world, call an NCO 'sir', and they'll respond: "Don't call me sir; I work for a living."

('Sir' is usually reserved for officers, and in UK & Commonwealth countries, Warrant Officers Class 1 & 2)