A surgical device, comprising: an elongate shaft (6, 34) having a longitudinal axis and a flexible portion extending along a length thereof, the flexible portion comprising a substantially cylindrical monolithic outer shell having an inner lumen extending therethrough and defining a longitudinal axis; a flexible divider separate from the shell and disposed within and extending through the inner lumen of the shell such that the divider separates the inner lumen into at least first and second elongate channels (90, 92), the divider being freely longitudinally slidable relative to the outer shell while being constrained from moving away from the longitudinal axis; a first articulation member extending through the first elongate channel in the inner lumen of the shell; a second articulation member extending through the second elongate channel in the inner lumen of the shell; and an end effector coupled to a distal end of the elongate shaft (6, 34) and coupled to the first and second articulation members such that axial translation of the articulation members within the first and second elongate channels (90, 92) is effective to cause the flexible portion to bend such that the end effector can be oriented to extend transverse to a longitudinal axis of the elongate shaft (6, 34); characterised in that the flexible divider includes a first divider and a second divider that are configured to be retained within the outer shell while being freely longitudinally slidable relative to the outer shell, the first divider has a plurality of first protrusions and the second divider has a plurality of second protrusions, which are together configured to maintain the first and second dividers (46a, 46b) at a predetermined distance apart along their lengths; wherein the first and second protrusions (66a, 66b) are alternatingly formed on facing surfaces of the first and second dividers (46a, 46b) so that protrusions formed on one of the dividers abut against an inner surface of the other one of the dividers in spaces defined between protrusions formed on that other divider. an elongate shaft (6, 34) having a longitudinal axis and a flexible portion extending along a length thereof, the flexible portion comprising a substantially cylindrical monolithic outer shell having an inner lumen extending therethrough and defining a longitudinal axis; a flexible divider separate from the shell and disposed within and extending through the inner lumen of the shell such that the divider separates the inner lumen into at least first and second elongate channels (90, 92), the divider being freely longitudinally slidable relative to the outer shell while being constrained from moving away from the longitudinal axis; a substantially cylindrical monolithic outer shell having an inner lumen extending therethrough and defining a longitudinal axis; a flexible divider separate from the shell and disposed within and extending through the inner lumen of the shell such that the divider separates the inner lumen into at least first and second elongate channels (90, 92), the divider being freely longitudinally slidable relative to the outer shell while being constrained from moving away from the longitudinal axis; a first articulation member extending through the first elongate channel in the inner lumen of the shell; a second articulation member extending through the second elongate channel in the inner lumen of the shell; and an end effector coupled to a distal end of the elongate shaft (6, 34) and coupled to the first and second articulation members such that axial translation of the articulation members within the first and second elongate channels (90, 92) is effective to cause the flexible portion to bend such that the end effector can be oriented to extend transverse to a longitudinal axis of the elongate shaft (6, 34); characterised in that the flexible divider includes a first divider and a second divider that are configured to be retained within the outer shell while being freely longitudinally slidable relative to the outer shell, the first divider has a plurality of first protrusions and the second divider has a plurality of second protrusions, which are together configured to maintain the first and second dividers (46a, 46b) at a predetermined distance apart along their lengths; wherein the first and second protrusions (66a, 66b) are alternatingly formed on facing surfaces of the first and second dividers (46a, 46b) so that protrusions formed on one of the dividers abut against an inner surface of the other one of the dividers in spaces defined between protrusions formed on that other divider.