Abstract: A roll fed labelling system and associated label are disclosed. The label (12) includes a triggering mark (28) formed of luminophor ink, i.e. containing a fluorescent optical brightening agent, that reflects visible light when irradiated with UV light. A modulated UV light is directed at the label and the modulated reflected visible light is detected and used to trigger a cutting mechanism to separate a single label from the remainder of the roll. The triggering mark need not visibly contrast with the surrounding graphics of the label and may be invisible in visible light. When producing the roll of labels, the amount of brightening agent may be controlled by monitoring the luminescence of the triggering mark relative to a reference level which may be derived with reference to a maximum luminescence of other parts of the label.