A sequencing system for a robotic storage and picking system. The storage system comprises a plurality of containers disposed in stacks 10 beneath a grid 22, the grid comprising a first set of tracks or rails and second set of tracks, the first and second sets of tracks being disposed substantially perpendicular to each other. The storage system 1 comprises a plurality of load handling devices operable on the grid, the load handling devices 30 lifting and depositing containers from and to the stacks. A portion of the grid 22 extends over a series of conveyor belts 142. The load handling devices being capable of depositing containers on to the conveyor belts into predetermined positions, the positions being fillable in any random order and multiple positions being fillable at any one time. Additional conveyors 144, 146 may extend substantially perpendicularly to the storage system 1 to transfer the containers from the conveyance means to a vehicle loading area. The conveyor belts may be independently movable such that all positions on each belt may be accessed and filled whilst the belt is stationary.