Data processing apparatus comprises processing circuitry to apply processing operations to one or more data items of a linear array comprising a plurality, n, of data items at respective positions in the linear array, the processing circuitry being configured to access an array of n×n storage locations, where n is an integer greater than one, the processing circuitry comprising: instruction decoder circuitry to decode program instructions; and instruction processing circuitry to execute instructions decoded by the instruction decoder circuitry; wherein the instruction decoder circuitry is responsive to an array access instruction, to control the instruction processing circuitry to access, as a linear array, a set of n storage locations arranged in an array direction selected, under control of the array access instruction, from a set of candidate array directions comprising at least a first array direction and a second array direction different to the first array direction.