s 19 Duty to display documents.
At all times while— (a) a person is registered in respect of any premises under section 7, or (b) an authorisation granted in respect of any premises under section 13(1) or 14 is for the time being in force, the person to whom the registration relates, or who holds the authorisation , as the case may be, shall cause copies of the certificate of registration or authorisation issued to him under this Act to be kept posted on the premises, in such characters and in such positions as to be conveniently read by persons having duties on those premises which are or may be affected by the matters set out in the certificate.