A steering column assembly comprising: a telescopic shroud having an outer shroud portion and an inner shroud portion, an end of the inner shroud portion extending into the outer shroud portion, a clamp rail fixed to an upper face of the inner shroud portion including a slot that extends axially along the inner shroud portion, the slot defining two opposing walls which each carry a rack of locking teeth, a clamp bolt that extends perpendicular to the shroud that may be rotated around its long axis by operation of a locking lever, a rocker comprising a body from which extends a lever arm, the body having an opening through which the clamp bolt passes, the rocker converting a rotation of the clamp bolt about its axis in a first direction into an upward motion of the lever arm and into a downward motion when the clamp bolt is rotated in the opposing second direction, a toothed block having two opposed racks of locking teeth that is connected to a carrier element, the carrier element in turn being connected to the lever arm of the rocker such that movement of the lever arm up and down causes movement of the carrier element up and down between an upper position and a lower position, whereby, with the carrier element in one of the upper position and the lower position, the toothed block is located within the slot such that one of the rows of teeth of the block engages a row of teeth of the slot, and whereby, with the carrier element in the other of the upper position and the lower position, the teeth of toothed block are held clear of the slot, and in which the connection between the clamp bolt and the carrier element defines a lost motion mechanism that prevents some of the rotational movement of the clamp bolt from being converted into movement of the toothed block. a telescopic shroud having an outer shroud portion and an inner shroud portion, an end of the inner shroud portion extending into the outer shroud portion, a clamp rail fixed to an upper face of the inner shroud portion including a slot that extends axially along the inner shroud portion, the slot defining two opposing walls which each carry a rack of locking teeth, a clamp bolt that extends perpendicular to the shroud that may be rotated around its long axis by operation of a locking lever, a rocker comprising a body from which extends a lever arm, the body having an opening through which the clamp bolt passes, the rocker converting a rotation of the clamp bolt about its axis in a first direction into an upward motion of the lever arm and into a downward motion when the clamp bolt is rotated in the opposing second direction, a toothed block having two opposed racks of locking teeth that is connected to a carrier element, the carrier element in turn being connected to the lever arm of the rocker such that movement of the lever arm up and down causes movement of the carrier element up and down between an upper position and a lower position, whereby, with the carrier element in one of the upper position and the lower position, the toothed block is located within the slot such that one of the rows of teeth of the block engages a row of teeth of the slot, and whereby, with the carrier element in the other of the upper position and the lower position, the teeth of toothed block are held clear of the slot, and in which the connection between the clamp bolt and the carrier element defines a lost motion mechanism that prevents some of the rotational movement of the clamp bolt from being converted into movement of the toothed block.