This article explores the possibility that the surgeon’s control over his or her environment is not complete and that, in certain circumstances, the final swab count can be distinguished from the ‘normal course of events’. We readily accept that most swabs and instruments are left inside patients simply as a result of substandard care but we cannot accept that this is invariably the case, and lessons from the common law are cited to illustrate the reasons why. We hope to persuade defendant lawyers that it might be worthwhile to tease out from surgeons under scrutiny how these factors may have influenced their practice on the day that a swab was retained.