A sensor assembly comprising: a sensor; a sensor housing that carries the sensor; a mounting member that pivotally engages with the sensor housing; an adjustment member for selecting an angular position of the sensor housing relative to the mounting member; and a locking mechanism for locking the sensor housing at the selected angular position relative to the mounting member; wherein the sensor housing comprises a first mounting element and a first adjustment element; wherein the mounting member comprises a second mounting element that pivotally engages with the first mounting element so as to permit pivotal movement of the sensor housing about a pivot axis relative to the mounting member; wherein the adjustment member comprises a second adjustment element that engages with the first adjustment element; wherein, when the locking mechanism is in an unlocked state, the adjustment member is slideable relative to the mounting member between a first location and a second location; wherein, when the adjustment member is moved relative to the mounting member between the first location and the second location, the engagement of the second adjustment element with the first adjustment element pivots the sensor housing about the pivot axis relative to the mounting member between a first angular position and a second angular position; wherein the angular position of the sensor housing relative to the mounting member is selectable by adjusting a location of the adjustment member relative to the mounting member; wherein, when the sensor housing is at the selected angular position relative to the mounting member and the locking mechanism is in a locked state, the adjustment member is prevented from sliding relative to the mounting member, and the engagement of the second adjustment element with the first adjustment element locks the sensor housing at the selected angular position relative to the mounting member; wherein the mounting member has a locking surface that is spaced from the pivot axis; wherein the adjustment member has a lock surface that faces towards the locking surface and is slideable relative to the locking surface when the locking mechanism is in the unlocked state; wherein, when the locking mechanism is in the locked state, the lock surface engages with the locking surface so as to prevent the adjustment member from moving relative to the mounting member; wherein the locking surface is planar; and the locking surface is parallel to the pivot axis; characterised in that the locking surface faces away from the pivot axis. a sensor; a sensor housing that carries the sensor; a mounting member that pivotally engages with the sensor housing; an adjustment member for selecting an angular position of the sensor housing relative to the mounting member; and a locking mechanism for locking the sensor housing at the selected angular position relative to the mounting member; wherein the sensor housing comprises a first mounting element and a first adjustment element; wherein the mounting member comprises a second mounting element that pivotally engages with the first mounting element so as to permit pivotal movement of the sensor housing about a pivot axis relative to the mounting member; wherein the adjustment member comprises a second adjustment element that engages with the first adjustment element; wherein, when the locking mechanism is in an unlocked state, the adjustment member is slideable relative to the mounting member between a first location and a second location; wherein, when the adjustment member is moved relative to the mounting member between the first location and the second location, the engagement of the second adjustment element with the first adjustment element pivots the sensor housing about the pivot axis relative to the mounting member between a first angular position and a second angular position; wherein the angular position of the sensor housing relative to the mounting member is selectable by adjusting a location of the adjustment member relative to the mounting member; wherein, when the sensor housing is at the selected angular position relative to the mounting member and the locking mechanism is in a locked state, the adjustment member is prevented from sliding relative to the mounting member, and the engagement of the second adjustment element with the first adjustment element locks the sensor housing at the selected angular position relative to the mounting member; wherein the mounting member has a locking surface that is spaced from the pivot axis; wherein the adjustment member has a lock surface that faces towards the locking surface and is slideable relative to the locking surface when the locking mechanism is in the unlocked state; wherein, when the locking mechanism is in the locked state, the lock surface engages with the locking surface so as to prevent the adjustment member from moving relative to the mounting member; wherein the locking surface is planar; and the locking surface is parallel to the pivot axis; characterised in that the locking surface faces away from the pivot axis.