HL 14 December 1989. These two appeals raise the question whether a decision of the SoS allowing an appeal against an enforcement notice on one of the grounds in Town and Country Planning Act 1971 s88 as amended by Local Government and Planning (Amendment) Act 1981 is capable of giving rise to an estoppel per rem judicatam or an issue estoppel. The first appeal arose from service of notice on T in February 1985 alleging breach of planning control due to a material change of use to a hostel for homeless families without the grant of planning permission. Appeals dismissed by the inspector. An appeal to the High Court was also dismissed but CA allowed T`s case. The SoS appealed to HL. The second appeal concerned an enforcement notice alleging a material change of use of a property. The various judicial stages followed the same pattern. In T`s, and by implication O`s, case HL rejected submissions by SoS that a statutory body cannot be fettered by estoppel and there was no justification f