I know that the updating of my doc is overdue - looks like I can now reference a very interesting circular on the ODPM website....:
http://www.odpm.gov.uk/stellent/groups/odpm_buildreg/documents/page/odpm_breg_037024.hcsp
http://www.odpm.gov.uk/stellent/groups/odpm_buildreg/documents/page/odpm_breg_037024.hcsp