"Subject to the following provisions of this Act, no person shall execute or cause to be executed any works for the demolition of a listed building or for its alteration or extension in any manner which would affect its character as a building of special architectural or historic interest, unless the works are authorised."
"Works of alteration or extension, on the other hand, may or may not have that effect, hence the qualification which applies to these words for the purposes of section 7."
"Where a defendant is charged with effecting unauthorised works of alteration by dismantling part of a listed building, was I wrong in law to decline to limit my consideration to those works as charged or was I correct in considering further unauthorised works of reconstruction or restoration to judge the effect on the special architectural or historic character of the building."
"Where it appears to the local planning authority -- (a) that any works have been or are being executed to a listed building in their area; and (b) that the works are such as to involve a contravention of section 9(1) or (2), they may, if they consider it expedient to do so having regard to the effect of the works on the character of the building as one of special architectural or historic interest, issue a notice under this section (in this Act referred to as a 'listed building enforcement notice')."