An access control device comprising: a locking mechanism for a moveable barrier, the moveable barrier having a first side and a second side, the locking mechanism having a locked and an unlocked state; a first locking and/or user interface component for positioning on the first side of the moveable barrier; and a second locking and/or user interface component for positioning on the second side of the moveable barrier; wherein the first and second locking and/or user interface (6, 7) components are arranged to be secured to an intermediary barrier member which has been provided with either a first set of through holes for a first alternative locking member or a second set of through holes for a second alternative locking member, the first set of through holes including at least one hole having a mutually distinct position from at least one hole included in the second set of through holes, and wherein the first and second locking and/or user interface components (6, 7) are both provided with fixing apertures (19, 21) corresponding to both the first and second sets of through holes so that the locking and/or user interface components (6, 7) can be secured via at least one fixing (16, 17) placed in at least one hole corresponding to either one of the first and second alternative locking members (6, 7) without requiring additional through holes in the intermediary barrier member; and further comprising a fixing member (16, 17) for extending through a set of through holes in the intermediary barrier member and into the fixing apertures (19, 21) in the first and second locking and/or user interface components (6, 7) for securing the first and second locking and/or user interface components to the intermediary barrier member; characterised in that the fixing member (16, 17) is configured to transfer power and/or data signals between the first and second locking and/or user interface components (6, 7); wherein the fixing member is a hollow tube and is operable to conduct power and/or data through the intermediary barrier member via one or more wires (14, 15) extending through the tube. a locking mechanism for a moveable barrier, the moveable barrier having a first side and a second side, the locking mechanism having a locked and an unlocked state; a first locking and/or user interface component for positioning on the first side of the moveable barrier; and a second locking and/or user interface component for positioning on the second side of the moveable barrier; wherein the first and second locking and/or user interface (6, 7) components are arranged to be secured to an intermediary barrier member which has been provided with either a first set of through holes for a first alternative locking member or a second set of through holes for a second alternative locking member, the first set of through holes including at least one hole having a mutually distinct position from at least one hole included in the second set of through holes, and wherein the first and second locking and/or user interface components (6, 7) are both provided with fixing apertures (19, 21) corresponding to both the first and second sets of through holes so that the locking and/or user interface components (6, 7) can be secured via at least one fixing (16, 17) placed in at least one hole corresponding to either one of the first and second alternative locking members (6, 7) without requiring additional through holes in the intermediary barrier member; and further comprising a fixing member (16, 17) for extending through a set of through holes in the intermediary barrier member and into the fixing apertures (19, 21) in the first and second locking and/or user interface components (6, 7) for securing the first and second locking and/or user interface components to the intermediary barrier member; characterised in that the fixing member (16, 17) is configured to transfer power and/or data signals between the first and second locking and/or user interface components (6, 7); wherein the fixing member is a hollow tube and is operable to conduct power and/or data through the intermediary barrier member via one or more wires (14, 15) extending through the tube.