As a general rule, any change that would result in loss of historical form, fabric or detail, such as internal fittings, should be kept to the minimum.
Fel rheol gyffredinol, dylid gwneud cyn lleied ag y bo modd o newidiadau a fydd yn arwain at golli ffurf, adeiladwaith neu fanylion hanesyddol, megis ffitiadau mewnol.