What criteria have to be met in order for it to approve the demolition of listed buildings, broken down by grade of building.

Government policy with regard to the demolition of listed buildings is set out in the Memorandum of Guidance on Listed Buildings and Conservation Areas, the document to which all planning authorities are directed by Scottish Office Development Department Circular No.13/1998 in their consideration of applications for listed building consent for works to all three categories of listed building.
Government policy is that no worthwhile building should be lost to our environment unless it is demonstrated beyond reasonable doubt that every effort has been exerted by all concerned to find practical ways of keeping it.
The memorandum advises planning authorities, when processing applications for consent to demolish, always to presume in favour of the retention of listed buildings and to consider demolition only where, after a full assessment by the authority of the importance, conditionand potential for re-use of the building by the present owner or another party, the case remains strong. The memorandum emphasises that careful assessment of all three of these issues is essential and reminds planning authorities that the fact that a strong case can be made in relation to one or two of them does not necessarily justify the loss of the building.