1. A method of tracking a target imaged in video footage, the method comprising the steps of: (i) identifying the target to be tracked in a first image frame, the target being located at a first position; (ii) generating a first population of sub-templates by sampling from a first template area defined around the first position; (iii) searching for an instance of each of the first population of sub-templates in a second image frame, and determining the location of each instance in the second image frame; (iv) identifying a second position of the target in the second image frame in dependence on the locations of the instances; (v) generating a second population of sub-templates, which second population comprises a selection of the first population of sub-templates, and a set of new sub-templates, the selection being chosen in dependence on the locations of the instances of each of the sub-templates in the second frame, and the set of new sub-templates being generated by sampling from a second template area defined around the second position; and (vi) iterating steps (iii) to (v) above in respect of further image frames, using the second population of sub-templates and the second position from a preceding iteration in place of the first population of sub-templates and the first position, thereby determining a series of target positions, and inferring the target track therefrom.