Open Access. The published version of this work has been reproduced here with permission of the Assistant Editor, BJGP. Royal College of General Practitioners. This article may be downloaded for personal use only. Permission to reproduce this article must be sought from the Royal College of General Practitioners. This article was first published in Br J Gen Pract 2007; 57(536): 225-230. More information about this publisher may be found at Royal College of General Practitioners. Copyright (2007) Royal College of General Practitioners.