Pump dispenser and containers

Pump dispenser comprising a container for fluid to be dispensed and a pump for dispensing fluid from the container, the container having a neck to which the pump is attached and the pump comprising

• a pump body defining a pump chamber, the pump body having a locating formation engaging the container neck, and a plunger reciprocable relative to the pump body in a pumping stroke to alter the volume of the pump chamber;
• a lock mechanism comprising respective lock formations of the plunger and pump body, the lock mechanism having a locked condition in which the plunger is locked against reciprocation and an unlocked condition in which the plunger can reciprocate for pumping, and in which a release movement of the lock mechanism from the locked condition comprises a relative rotation of the plunger and pump body around an axis of the plunger, and optionally also
• a catch mechanism comprising respective catch formations of the plunger and pump body which are engageable selectively in a locked condition of the lock mechanism, to prevent or inhibit the release movement thereof, and
• wherein:
• i) a body/neck rotation stop mechanism comprising a first interlock formation provided on the container neck and having a circumferentially-directed abutment face and a second interlock formation provided on the pump body and having a cooperating, circumferentially-directed abutment face, and ii) the first and second interlock formations are configured in an annular interface between the neck and the pump body so that, cumulatively, at least 80% of the annular interface consists of one or more clearance segments, said clearance segment(s) extending between the circumferentially-directed abutment faces of the first interlock formation and the second interlock formation so as to accommodate rotational movement of the first and second and interlock formations and to inhibit relative rotation between the container and the pump when the first and second interlock formations are engaged.