Embodiments of the invention provide an arrangement where a surgical instrument having a shaft with an end effector mounted thereon is provided with a rotation wheel configured to allow the user to rotate the shaft during use into a desired angular position. In order to allow for a compact and reliable mechanism the rotation wheel, the outer edge of which is generally accessible at the external surface of the instrument, has an internal space around the axis of the wheel within which is provided part of an actuation mechanism for the end effector. In order to allow for rotation of the actuation mechanism with the end effector, the part of the actuation mechanism located within the wheel rotationally mutually engages with the inner surface of the internal space within the wheel, such that rotation of the wheel by the user causes the actuation mechanism to rotate, which in turn rotates the shaft on which the end effector is mounted. Such an arrangement provides benefits that it allows otherwise redundant space within the rotation wheel to be used to accommodate part of the actuation mechanism for the end effector, thus improving compactness of the device, whilst still allowing rotation of the end-effector and its corresponding actuation mechanism. <；Figure 32>；
