Section 483. Signs advertising services as attorney at law

It shall be
  unlawful for any person to maintain on real property  or  to  permit  or
  allow  any  other  person  to  maintain, on such property a sign, in any
  language, to the effect that an attorney-at-law or  legal  services  are
  available  therein  unless  the  full name of the attorney-at-law or the
  firm rendering such services is set forth thereon.  In  any  prosecution
  for  violation of the provisions of this section the existence of such a
  sign on real property shall be presumptive evidence that it  was  placed
  or  permitted  to  exist  thereon  with the knowledge and consent of the
  person or persons in possession of said premises.