The former President of Ireland, Mary McAleese has called Boris Johnson’s efforts to change the withdrawal agreement from the European Union a threat to the Northern Ireland peace process. She said the move, if it happens, would be a “vile and immoral act”.

Professor McAleese, currently Professor of Children, Law and Religion at Theology and Religious Studies, University of Glasgow, served two terms as President between 1997 and 2011 and oversaw the visit of the Queen to Ireland, the first visit by a British monarch in a century. Speaking to The Herald Magazine, she said she hoped reports of the British government’s desire to change the withdrawal agreement are not true.

“I think we’re coming towards the end of a negotiation and the lawyer in me understands that as you come to the end game the resolution of a very significant negotiation sometimes the temptation is to bluster and be the braggart and to raise the stakes in order to maximise your negotiating position,” she said. “I am hoping that that is all this is with Boris Johnson.

“Because if it wasn’t, I’d be forced to say that toying as they are with the Northern Ireland peace process after all that has gone into creating it and sustaining it would be a vile and immoral act.

“The withdrawal agreement was negotiated in good faith by the European Union, and of course constructed by the United Kingdom and indeed by Boris, and hailed by him as a great deal. He now, of course, contradicts himself.

“He really needs to listen to the voices that have been raised in his own party, including former Prime Ministers. The Lord Chief Justice of Northern Ireland, who, God knows, you don’t hear too often speaking outside of the court, was moved to point out that this is deeply, deeply unprincipled.

“This is the first treaty that Britain will have made as a non-member of the European Union and it doesn’t augur too well to sign one thing and then contradict it.

“But in so far as it trammels on the Good Friday Agreement, I just think there’s a realm of immorality about it that is deeply, deeply worrying."

In her interview with the Herald Magazine tomorrow McAleese talks of growing up in Belfast at the height of the Troubles and of the Queen’s visit to Dublin in 2011.