Prior to subject randomisation, sealed envelopes will be prepared containing the treatment manual for the two treatment arms. The assessor will assign consenting participants a unique study number and the anonymised data will be forwarded to the named research officer at the Brighton and Sussex Clinical Trials Unit (B&S CTU). The officer will enter the data into the software package 'sealed envelope' that will process the data and assign the subject to the treatment or placebo group. An E-mail containing group allocation will then be sent to the assessor. The patient will then be transferred to the reception of the physiotherapy department where the appropriately numbered envelop will be placed with the physiotherapy notes and the patient booked for their initial physiotherapy session. The group allocation of each patient will only be available to the treating physiotherapist when the envelope containing the manual is opened at the initial physiotherapy consultation. The physiotherapist will be instructed not to advise the patient to which group they have been allocated.