Northern Ireland’s Attorney General John Larkin will appeal the landmark High Court ruling allowing a legally-binding humanist wedding ceremony to go ahead.

Lawyers for Laura Smyth, who brought the successful case, received a Notice of Appeal from the Attorney General on Friday night.

Humanists UK, formerly known as the British Humanist Association, said it was “not clear, at this stage, whether this action even has the support of the original respondents to the challenge”, the General Register Office (GRO) and the Department of Finance.

Humanists UK supported the couple in their court action.

Ms Smyth and her fiancé Eunan O’Kane are due to be married on 22 June. The various orders of the High Court remain legally valid and effective and they intend to marry in accordance with those orders.

The couple have contacted the GRO to confirm a legally valid marriage can take place on their intended date.

Andrew Copson, chief executive of Humanists UK, said: “The Attorney General is going to extraordinary lengths at public expense just to stop two people who love each other from getting legally married in accordance with their beliefs.

“We hope that common decency might still prevail and that the Attorney General will reconsider this misconceived appeal.

“If an appeal does proceed, we at least hope it will be expedited and heard in advance of the wedding date or, if that is not possible, that the Orders made by Mr Justice Colton this morning will remain valid and not be set aside in the interim.

“If the proposed appeal does proceed we understand that it will be robustly defended by Laura in order to vindicate the humane, carefully considered and entirely lawful judgment of Mr Justice Colton.

“Laura and Eunan deserve the right to marry in accordance with their beliefs just as much as any religious couple.”

Humanist marriages have been legally recognised in Scotland since 2005 and in the Republic of Ireland since 2012.

Over the weekend, the Humanist Society Scotland celebrated the 50,000th person to be married in one of its ceremonies.