An object handling and retrieval system comprising a storage system, a plurality of load handling devices, at least one drop off point and a workstation, the storage system comprising two substantially perpendicular sets of rails forming a grid above a workspace, the workspace comprising a plurality of stacked containers, the robotic load handling devices operating on the grid above the workspace, the load handling devices comprising a body mounted on wheels (34, 36), a first set of wheels being arranged to engage with at least two rails of the first set of rails, a second set of wheels being arranged to engage with at least two rails of the second set of rails, the first set of wheels being independently moveable and driveable with respect to the second set of wheels such that when in motion only one set of wheels (34, 36) is engaged with the grid at any one time thereby enabling movement of the load handling device along the rails to any point on the grid above any stack of containers by driving only the set of wheels (34, 36) engaged with the rails, wherein at least one drop off point is adapted to engage with a sequencing portion, the sequencing portion being adapted so as to receive containers delivered to the at least one drop off point by a load handling device and move said delivered containers to the workstation in a predetermined order, the sequencing portion comprising a frame located adjacent the storage system, the frame being provided with a plurality of container storage positions (140, 240, 340), the sequencing portion being further provided with moving means (170, 270, 370) for moving containers from the container storage positions (140, 240, 340) to the workstation in a predetermined order, said predetermined order being irrespective of the order in which the containers reached the drop off point such that objects located within the containers may be accessed at the workstations, wherein the moving means (170, 270, 370) comprises at least one picking means located adjacent the frame, the picking means being adapted so as to select a predetermined container from the frame and transport the container to the workstation, and wherein a container may be removed and or replaced from a modified stack of containers, and characterized in that, the modified stack of containers may be accessed from one side by the moving means using means for supporting all the containers above the target container whilst removing the target container onto the moving means. a storage system, a plurality of load handling devices, at least one drop off point and a workstation, the storage system comprising two substantially perpendicular sets of rails forming a grid above a workspace, the workspace comprising a plurality of stacked containers, the robotic load handling devices operating on the grid above the workspace, the load handling devices comprising a body mounted on wheels (34, 36), a first set of wheels being arranged to engage with at least two rails of the first set of rails, a second set of wheels being arranged to engage with at least two rails of the second set of rails, the first set of wheels being independently moveable and driveable with respect to the second set of wheels such that when in motion only one set of wheels (34, 36) is engaged with the grid at any one time thereby enabling movement of the load handling device along the rails to any point on the grid above any stack of containers by driving only the set of wheels (34, 36) engaged with the rails, wherein at least one drop off point is adapted to engage with a sequencing portion, the sequencing portion being adapted so as to receive containers delivered to the at least one drop off point by a load handling device and move said delivered containers to the workstation in a predetermined order, the sequencing portion comprising a frame located adjacent the storage system, the frame being provided with a plurality of container storage positions (140, 240, 340), the sequencing portion being further provided with moving means (170, 270, 370) for moving containers from the container storage positions (140, 240, 340) to the workstation in a predetermined order, said predetermined order being irrespective of the order in which the containers reached the drop off point such that objects located within the containers may be accessed at the workstations, wherein the moving means (170, 270, 370) comprises at least one picking means located adjacent the frame, the picking means being adapted so as to select a predetermined container from the frame and transport the container to the workstation, and wherein a container may be removed and or replaced from a modified stack of containers, and characterized in that, the modified stack of containers may be accessed from one side by the moving means using means for supporting all the containers above the target container whilst removing the target container onto the moving means.