Sergeant major instructor (SMI) is a British Army appointment held by warrant officers class 1 in the Small Arms School Corps and the Army Physical Training Corps and by some WO1s in the Royal Engineers.

Cadet forces

It is also a rank held by some of the civilian^[1] adult instructors in the Army Cadet Force, ranking between staff sergeant instructor and regimental sergeant major instructor.^[2] SMIs of the ACF do not hold a warrant and thus are not warrant officers, although their badges of rank are similar to those of an army warrant officer class 2.^[3]^[4]

References

^ The Army Cadet Force Manual. Ministry of Defence. pp. 5–1. 5.002. AI are voluntary youth workers appointed for service within the youth organisation that is the Army Cadet Force. For administrative convenience, they have similar conditions of service as part-time Crown Servants working for the Secretary of State for Defence; they are not members of the Armed Forces. An AI is not therefore subject to military law but is required to wear military uniform and rank while involved in ACF activities and is expected to act in accordance with the Values and Standards of the British Army. An AI carries out either general duties with the ACF or a specialist role by reason of possessing a special skill or qualification of use to the ACF.
^ "Potential Instructors & Adult Instructors". There are two routes of employment in the ACF; the adult leader without previous military experience would start as a probationary instructor denoted by the wearing on red shoulder boards and having attended and passed the Initial Training Course (a 7 day course normally held at Annual Camp or Preston) they would become a sergeant instructor. Promotion is available to sergeant major instructor, all of these levels are civilian based and their employment comes within a contract of employment.
^ "ACF website". The ACF isn't part of the Army. Okay, there are uniforms, traditions and badges of rank, but all adults in the ACF are essentially youth workers. And don't worry, there's no danger of military call-up.
^ "Instructor Ranks". ACF. Adult instructors who hold "non-commissioned officer" army ranks. On appointment you will be a Sergeant Instructor and there exists the opportunity to rise to Regimental Sergeant Major Instructor (RSMI). Along the way you are likely to be a detachment instructor and later a detachment commander. From there you will likely take responsibility for a number of detachments as a Company Sergeant Major before rising to the rank of RSMI where you will be the senior non-commissioned rank in your county!