A rotary actuator comprising: a housing; a clamp arrangement (30; 230, 330) rotatably mounted to the housing, the clamp arrangement (30; 230, 330) operable to apply a clamping force to a shaft (16; 316), the clamp arrangement (30; 230, 330) including: a first bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing; a second bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing; a gear portion (90; 290; 390) interposed between the first and second bearings; characterised by a clamp for applying the clamping force to the shaft (16; 316), the clamp and the gear portion (90; 290; 390) positioned at a same axial position along the shaft axis; and wherein the clamp arrangement (30; 230; 330) includes a pair of casing member halves, the casing member halves providing the first and second bearings, the casing member halves attached to the gear portion (90; 290; 390) such that rotation of the gear portion (90; 290; 390) about the axis rotates the casing member halves, and wherein the first and second bearings define apertures that are coaxial about the shaft axis, the apertures for receiving the shaft (16; 316) therethrough along the shaft axis. a housing; a clamp arrangement (30; 230, 330) rotatably mounted to the housing, the clamp arrangement (30; 230, 330) operable to apply a clamping force to a shaft (16; 316), the clamp arrangement (30; 230, 330) including: a first bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing; a second bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing; a gear portion (90; 290; 390) interposed between the first and second bearings; characterised by a clamp for applying the clamping force to the shaft (16; 316), the clamp and the gear portion (90; 290; 390) positioned at a same axial position along the shaft axis; and wherein the clamp arrangement (30; 230; 330) includes a pair of casing member halves, the casing member halves providing the first and second bearings, the casing member halves attached to the gear portion (90; 290; 390) such that rotation of the gear portion (90; 290; 390) about the axis rotates the casing member halves, and wherein the first and second bearings define apertures that are coaxial about the shaft axis, the apertures for receiving the shaft (16; 316) therethrough along the shaft axis. a first bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing; a second bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing; a gear portion (90; 290; 390) interposed between the first and second bearings; characterised by a clamp for applying the clamping force to the shaft (16; 316), the clamp and the gear portion (90; 290; 390) positioned at a same axial position along the shaft axis; and wherein the clamp arrangement (30; 230; 330) includes a pair of casing member halves, the casing member halves providing the first and second bearings, the casing member halves attached to the gear portion (90; 290; 390) such that rotation of the gear portion (90; 290; 390) about the axis rotates the casing member halves, and wherein the first and second bearings define apertures that are coaxial about the shaft axis, the apertures for receiving the shaft (16; 316) therethrough along the shaft axis.