See The General Regulatory Council for Complementary Therapies “Code of Conduct” http://www.grcct.org/about-us/code-of-conduct/
See SECTION 3 : PATIENT/CLIENT RECORDS AND CONFIDENTIALITY
Text includes:
“Patient/client records (as defined in 3.3.2 above) provide valuable information. Such records shall be retained in safe custody by the practitioner to whom they belong for a period of six years from the date of the last treatment.”