The 1990 Act only applies to England and Wales, but it, too, has been widely amended as historic environment policy in England and Wales has diverged.
Dim ond i Gymru a Lloegr y mae Deddf 1990 yn gymwys, ond mae’r ddeddf honno hefyd wedi'i diwygio'n helaeth gan fod polisi amgylchedd hanesyddol yng Nghymru a Lloegr wedi mynd i gyfeiriadau gwahanol.