A master-slave robotic system comprising: a master input device movable in a plurality of degrees of freedom; at least one slave coupled to the master input device, the at least one slave movable in a plurality of degrees of freedom in response to the master input device, the at least one slave comprising an articulate endoscope (310"), the endoscope (310") comprising an elongate shaft (14") having a working end, a proximal end, and a shaft axis between the working end and the proximal end; a flexible wrist (10") having a distal end and a proximal end, the proximal end of the wrist (10") connected to the working end of the elongate shaft (14"); a camera having at least one camera lens (314") installed at the distal end of the wrist (10"), the camera lens (314") for acquiring an image of a surgical site; and a plurality of actuation links connecting the wrist (10") to the proximal end of the elongate shaft (14") such that the links are actuatable to provide the wrist (10") with at least one wrist degree of freedom; the master-slave robotic system further comprising: a display coupled to the camera for showing the acquired image; and means for changing a frame of reference used by the master input device for controlling any or all of the plurality of degrees of freedom of the slave, including the at least one wrist degree of freedom, the frame of reference being selectable between a camera-reference frame and a world-reference frame, and characterised in that the means for changing is configured to change the frame of reference so that the frame of reference used for controlling a first of the plurality of degrees of freedom is different from the frame of reference used for controlling a second of the plurality of degrees of freedom. a master input device movable in a plurality of degrees of freedom; at least one slave coupled to the master input device, the at least one slave movable in a plurality of degrees of freedom in response to the master input device, the at least one slave comprising an articulate endoscope (310"), the endoscope (310") comprising an elongate shaft (14") having a working end, a proximal end, and a shaft axis between the working end and the proximal end; a flexible wrist (10") having a distal end and a proximal end, the proximal end of the wrist (10") connected to the working end of the elongate shaft (14"); a camera having at least one camera lens (314") installed at the distal end of the wrist (10"), the camera lens (314") for acquiring an image of a surgical site; and a plurality of actuation links connecting the wrist (10") to the proximal end of the elongate shaft (14") such that the links are actuatable to provide the wrist (10") with at least one wrist degree of freedom; the master-slave robotic system further comprising: a display coupled to the camera for showing the acquired image; and means for changing a frame of reference used by the master input device for controlling any or all of the plurality of degrees of freedom of the slave, including the at least one wrist degree of freedom, the frame of reference being selectable between a camera-reference frame and a world-reference frame, and characterised in that the means for changing is configured to change the frame of reference so that the frame of reference used for controlling a first of the plurality of degrees of freedom is different from the frame of reference used for controlling a second of the plurality of degrees of freedom. a display coupled to the camera for showing the acquired image; and means for changing a frame of reference used by the master input device for controlling any or all of the plurality of degrees of freedom of the slave, including the at least one wrist degree of freedom, the frame of reference being selectable between a camera-reference frame and a world-reference frame, and characterised in that the means for changing is configured to change the frame of reference so that the frame of reference used for controlling a first of the plurality of degrees of freedom is different from the frame of reference used for controlling a second of the plurality of degrees of freedom.