A method for clustering a plurality of content items. The method comprises, determining intervals between at least some of the content items, and then selecting a seed pair of content items using the determined intervals. The seed pair is then assigned to a current cluster, before an interval is determined between one of the content items in the current cluster and a neighboring one of the content items. The interval is then compared to a predetermined criterion in response to a successful comparison, the content item is assigned to the cluster.