Closures with means for discouraging unauthorised opening or removal thereof, with or without indicating means, e.g. child-proof closures openable or removable by the combination of plural actions requiring the combination of simultaneous actions, e.g. depressing and turning, lifting and turning, maintaining a part and turning another one {the closure comprising a screw cap whose threads are shaped to accommodate blocking elements and the closure is removed after first applying axial force to unblock it and allow it to be unscrewed}