A sorting system comprising: a sorting conveyor including: a plurality of selectively rotatable rollers arranged in a grid of multiple rows and columns of individually controlled grid cells along the sorting conveyor; characterised in that the system comprises: a conveyor belt advancing in a direction of belt travel and having a plurality of article- supporting belt rollers extending through the thickness of the conveyor belt and rotatable in a direction transverse to the direction of belt travel and wherein the selectively rotatable rollers have bearing surfaces contacting and selectively rotating the belt rollers passing through the grid cells; a control system which determines the size and position of each article (P1; P2) on entering the sorting conveyor, and which computes a trajectory for each article along the sorting conveyor from the article's entry to its exit from the sorting conveyor from the article's size and position, and which selectively controls the rollers in each grid cell according to the trajectories computed for the articles to actuate and deactuate the rollers to divert articles across the sorting conveyor along the computed trajectories. a sorting conveyor including: a plurality of selectively rotatable rollers arranged in a grid of multiple rows and columns of individually controlled grid cells along the sorting conveyor; characterised in that the system comprises: a conveyor belt advancing in a direction of belt travel and having a plurality of article- supporting belt rollers extending through the thickness of the conveyor belt and rotatable in a direction transverse to the direction of belt travel and wherein the selectively rotatable rollers have bearing surfaces contacting and selectively rotating the belt rollers passing through the grid cells; a control system which determines the size and position of each article (P1; P2) on entering the sorting conveyor, and which computes a trajectory for each article along the sorting conveyor from the article's entry to its exit from the sorting conveyor from the article's size and position, and which selectively controls the rollers in each grid cell according to the trajectories computed for the articles to actuate and deactuate the rollers to divert articles across the sorting conveyor along the computed trajectories. a plurality of selectively rotatable rollers arranged in a grid of multiple rows and columns of individually controlled grid cells along the sorting conveyor; characterised in that the system comprises: a conveyor belt advancing in a direction of belt travel and having a plurality of article- supporting belt rollers extending through the thickness of the conveyor belt and rotatable in a direction transverse to the direction of belt travel and wherein the selectively rotatable rollers have bearing surfaces contacting and selectively rotating the belt rollers passing through the grid cells; a control system which determines the size and position of each article (P1; P2) on entering the sorting conveyor, and which computes a trajectory for each article along the sorting conveyor from the article's entry to its exit from the sorting conveyor from the article's size and position, and which selectively controls the rollers in each grid cell according to the trajectories computed for the articles to actuate and deactuate the rollers to divert articles across the sorting conveyor along the computed trajectories. a conveyor belt advancing in a direction of belt travel and having a plurality of article- supporting belt rollers extending through the thickness of the conveyor belt and rotatable in a direction transverse to the direction of belt travel and wherein the selectively rotatable rollers have bearing surfaces contacting and selectively rotating the belt rollers passing through the grid cells; a control system which determines the size and position of each article (P1; P2) on entering the sorting conveyor, and which computes a trajectory for each article along the sorting conveyor from the article's entry to its exit from the sorting conveyor from the article's size and position, and which selectively controls the rollers in each grid cell according to the trajectories computed for the articles to actuate and deactuate the rollers to divert articles across the sorting conveyor along the computed trajectories.