Back pain causes considerable suffering and is a major financial burden, costing the NHS an estimated £1.1 billion annually (Maniadakis and Gray 2000) and representing the second largest cause of absence from work (Young and Bhaumik, 2011). Chronic low back pain (CLBP), defined as pain lasting more than 12 weeks, is responsible for 80% of this cost (Department of Health, 2009). Physiotherapy is a common treatment for CLBP, with 1.26 million patients referred to NHS physiotherapists at a cost of £150 million per annum (Maniadakis and Gray, 2000). Several forms of physiotherapy are recommended for CLBP, including exercises, manual therapy and back classes (NICE, 2009). The type of physiotherapy varies considerably in duration and content, despite evidence that different treatments have similar effects (Critchley et al, 2007). Most trials show no clear superiority for any treatment, with the majority leading to only moderate improvement (Artus et al 2010).