Mr Brown was chairman of Bellaghy Wolfe Tones GAA Club and was locking the gates to its training ground on 12 May 1997 when he was abducted by loyalist paramilitaries.

He was found dead next to his burning car the next morning, having been beaten and shot six times in the head.

High Court judge Mr Justice Humphreys ruled in mid-December that a public inquiry into the murder was now necessary to satisfy the UK’s obligations under Article 2 of the European Convention on Human Rights (ECHR).

He made an order of mandamus compelling the Northern Ireland secretary to hold an inquiry under the Inquiries Act 2005, which the judge acknowledged was “unusual and exceptional”, but “fully justified on the facts of this case and on a proper application of legal principle”.

The UK government lodged a notice of appeal on 31 December 2024, which has been expedited to a full hearing on 16 January 2025.

An inquest into Mr Brown’s death was discontinued last year because of the volume of material being withheld on the grounds of national security. The coroner wrote to then Northern Ireland secretary Chris Heaton-Harris to call for an independent public inquiry.

The new Northern Ireland secretary, Hilary Benn, said in September that he did not agree with calls for an inquiry and that the murder should instead be investigated by the controversial Independent Commission for Reconciliation and Information Recovery (ICRIR).

Mr Brown’s family, represented by Belfast firm KRW LAW LLP, has criticised the decision to appeal the High Court ruling.