A latch mechanism having a longitudinal axis and comprising: an upper latch assembly (131, 181) and a lower latch assembly (134, 183), said upper latch assembly (131, 181) and the lower latch assembly (134, 183) being coaxially aligned, and wherein: (a.1) an upper latch component (401, 185) is carried on and rotationally coupled to the upper latch assembly (133, 181); (a.2) a lower latch component (491, 189) is carried on and rotationally coupled to the lower latch assembly (134, 183); (a.3) the upper latch component (401, 185) and the lower latch component (491, 189) are movable between: • a latched position, in which relative axial separation of the upper latch assembly (133, 181) and the lower latch assembly (134, 183) is constrained by mating engagement of the upper latch component (401, 185) and the lower latch component (491, 189); and • an unlatched position, in which the upper latch component (401, 185) and the lower latch component (491, 189) are disengaged and relative axial separation of the upper latch assembly (133, 181) and the lower latch assembly (134, 183) is permitted within a defined range; in response to relative rotation and associated torque between the upper latch assembly (133, 181) and the lower latch assembly (134, 183) in a first rotational direction; characterised in that the latch mechanism further comprises a latch release mechanism carrying an axially-movable land element (450, 171) and having actuation means for inducing relative rotation and an associated latch actuation torque sufficient to move the upper latch component (401, 185) and the lower latch component (491, 189) from the latched position to the unlatched position in response to axial movement of the land element (450, 171) resulting from axial force externally applied to the land element (450, 171). (a.1) an upper latch component (401, 185) is carried on and rotationally coupled to the upper latch assembly (133, 181); (a.2) a lower latch component (491, 189) is carried on and rotationally coupled to the lower latch assembly (134, 183); (a.3) the upper latch component (401, 185) and the lower latch component (491, 189) are movable between: • a latched position, in which relative axial separation of the upper latch assembly (133, 181) and the lower latch assembly (134, 183) is constrained by mating engagement of the upper latch component (401, 185) and the lower latch component (491, 189); and • an unlatched position, in which the upper latch component (401, 185) and the lower latch component (491, 189) are disengaged and relative axial separation of the upper latch assembly (133, 181) and the lower latch assembly (134, 183) is permitted within a defined range; in response to relative rotation and associated torque between the upper latch assembly (133, 181) and the lower latch assembly (134, 183) in a first rotational direction; characterised in that the latch mechanism further comprises a latch release mechanism carrying an axially-movable land element (450, 171) and having actuation means for inducing relative rotation and an associated latch actuation torque sufficient to move the upper latch component (401, 185) and the lower latch component (491, 189) from the latched position to the unlatched position in response to axial movement of the land element (450, 171) resulting from axial force externally applied to the land element (450, 171). • a latched position, in which relative axial separation of the upper latch assembly (133, 181) and the lower latch assembly (134, 183) is constrained by mating engagement of the upper latch component (401, 185) and the lower latch component (491, 189); and • an unlatched position, in which the upper latch component (401, 185) and the lower latch component (491, 189) are disengaged and relative axial separation of the upper latch assembly (133, 181) and the lower latch assembly (134, 183) is permitted within a defined range;