A mechanical clutch (10, 110) for selectively mechanically connecting and disconnecting a rotational drive member (20, 120) and a rotational driven member (22, 122) within a locking mechanism; the mechanical clutch comprising:- a drive member (20, 120) comprising a disc for rotation around an axis of rotation; a driven member for rotation around said axis of rotation (A-A); at least a clutch pin (30A, 30B, 130) which selectively engages with the drive member (20, 120) to selectively mechanically and rotationally link the drive (20, 120) and driven (22, 122) member to one another; a clutch pin engagement surface (31, 31A, 31B, 131) provided on the or each clutch pin (30A, 30B, 130); and a corresponding clutch pin engagement surface provided on the drive member (20, 120) in the form of recesses (28A, 28B, 28C, 128) on a face thereof such that, when the engaged drive (20, 120) and driven (22, 122) members are rotated against a magnitude of rotational resistance which is below a threshold magnitude of rotational resistance, the respective clutch pin engagement surfaces (31, 31A, 31B, 131) of the or each clutch pin (30A, 30B, 130) and drive member (20, 120) will co-act with one another to retain said rotational connection between the drive (20, 120) and driven (22, 122) member and, when the drive and driven members are rotated against a magnitude of rotational resistance which is above the threshold magnitude of rotational resistance the respective clutch pin engagement surfaces (31, 31A, 31B, 131) of the or each clutch pin (30A, 30B, 130) and drive (20, 120) member will co-act with one another to urge the or each clutch pin out of rotational driving engagement between the drive and driven member. a drive member (20, 120) comprising a disc for rotation around an axis of rotation; a driven member for rotation around said axis of rotation (A-A); at least a clutch pin (30A, 30B, 130) which selectively engages with the drive member (20, 120) to selectively mechanically and rotationally link the drive (20, 120) and driven (22, 122) member to one another; a clutch pin engagement surface (31, 31A, 31B, 131) provided on the or each clutch pin (30A, 30B, 130); and a corresponding clutch pin engagement surface provided on the drive member (20, 120) in the form of recesses (28A, 28B, 28C, 128) on a face thereof such that, when the engaged drive (20, 120) and driven (22, 122) members are rotated against a magnitude of rotational resistance which is below a threshold magnitude of rotational resistance, the respective clutch pin engagement surfaces (31, 31A, 31B, 131) of the or each clutch pin (30A, 30B, 130) and drive member (20, 120) will co-act with one another to retain said rotational connection between the drive (20, 120) and driven (22, 122) member and, when the drive and driven members are rotated against a magnitude of rotational resistance which is above the threshold magnitude of rotational resistance the respective clutch pin engagement surfaces (31, 31A, 31B, 131) of the or each clutch pin (30A, 30B, 130) and drive (20, 120) member will co-act with one another to urge the or each clutch pin out of rotational driving engagement between the drive and driven member.