A delivery and deployment system for a self-expanding stent comprises a proximal handle having a rotatable thumbscrew and a sliding component which is attached to a distal stent restraining sheath. A rigid open coil spring is provided for converting rotation of the thumbscrew into translation of the sliding component). The spring is attached to the thumbscrew. The sliding component is located between adjacent coils of the spring. Rotation of the thumbscrew twists the spring and slowly slides the sliding component and hence the distal sheath in the proximal direction to uncover the stent, removing the constraint on the stent which is accurately deployed at the site of interest. The handle has a guide elongate channel which constrains the sliding component so that it cannot move in a rotational direction.