It conducted undercover surveillance operations against suspected members of Irish republican and Ulster loyalist paramilitary groups.

Members of the unit were recruited from regular Army battalions and trained in an eight-week course by the Special Air Service (SAS).

An April 1974 briefing for Prime Minister Harold Wilson states: Authors claiming to be former members of the unit describe an organisation[7][8][9][10][11] with a depot in Great Britain and four operational detachments in Northern Ireland.

Candidates, both male and female, volunteered for special duties for periods of 18–36 months, before being returned to a parent unit.

[4] 14 Intelligence was accused of acting in collusion with loyalist paramilitaries by former intelligence personnel Fred Holroyd and Colin Wallace in regards to the death of senior Provisional Irish Republican Army member John Francis Green, the Miami Showband killings and the Dublin and Monaghan bombings.