“(“P”) is undergoing detention in legal custody after the conclusion of criminal proceedings if it is a period during which P is detained in a hospital or similar institution in Northern Ireland as a person suffering from a mental disorder unless—

(a)

P is being detained under Article 53 of the Mental Health (Northern Ireland) Order 19867 (removal to hospital of persons serving sentences of imprisonment etc.), and

(b)

in any case where there is in relation to P a release date within the meaning of Article 56(3) of that Order8 (further provisions as to prisoners under sentence), P is being detained on or before the day which the Secretary of State certifies to be that release date.”; and