This case contains the first binding decision by a UK Court of Appeal — here, the Northern Ireland Court of Appeal — on a claim for authorisation of treatment abroad under the EU–UK Social Security Co-ordination Protocol (SSC). While dismissing the appeal due to the subsequent loss of legal interest as 'academic' under the Salem principle, the Court of Appeal provided a detailed obiter dictum on the interpretation of Article 18 SSC. The judgment addresses not only the substantive question of whether diagnostic services are covered by the term ‘treatment’ in Article 18 SSC, but also the procedural question of the extent to which UK courts may rely on ECJ case law when interpreting the Protocol after Brexit.