http://www.legislation.gov.uk/asc/2026/6/section/140Planning (Wales) Act 2026enStatute Law Database2026-06-16Expert Participation2026-04-28 PART 4ENFORCEMENTFurther provisions about effect of enforcement noticesGrounds for appeal not to be raised in other proceedings 140 1 The validity of an enforcement notice may not be questioned, on any of the grounds on which an appeal may be made under section 131, in any proceedings except an appeal under that section. 2 Subsection (1) does not apply to proceedings for an offence under section 138 against a person who— a has held an interest in the land to which the enforcement notice relates since before the notice was issued, b was not served with a copy of the notice, and c satisfies the court— i that the person did not know, and could not reasonably have been expected to know, of the existence of the notice, and ii that the person’s interests have been substantially prejudiced by the failure to serve a copy of the notice. S. 140 not in force at Royal Assent, see s. 409(2)