By Dominic McGrath, PA and Q Radio News
A church service is taking place in Armagh on Thursday to mark the centenary of Northern Ireland's formation and partition of Ireland.
The Prime Minister Boris Johnson has travelled to the region for the cross community event.
He is among politicians from both sides of the border at the Service of Reflection and Hope, which has been organised by church leaders.
The Queen had been set to attend but was unable to travel after she fell ill.
She is being represented by the Lord-Lieutenant of Co Armagh Lord Caledon.
The Queen during a previous visit to Northern Ireland
Around 150 people are attending the service, including a number of schoolchildren.
The sermon will be delivered by the president of the Methodist Church in Ireland, Dr Sahr Yambasu. Originally from Sierra Leone, he is the first African-born leader of one of Ireland’s main churches.
The service became the centre of a row last month after the president of Ireland, Michael D Higgins, declined an invitation to attend because he believed it was not politically neutral.
The Irish government will be represented by Foreign Affairs Minister Simon Coveney and chief whip Jack Chambers.
Earlier this month, Taoiseach Micheal Martin said his government’s stance “doesn’t in any way undermine the position of the president”.
He said the president, as the head of state, “comes at these issues from a different perspective”.
President of Ireland Michael D Higgins
Sinn Fein has also decided not to attend the event.
However, DUP leader Sir Jeffrey Donaldson and First Minister Paul Givan will be there, along with Ulster Unionist leader Doug Beattie, SDLP leader Colum Eastwood and Alliance party leader Naomi Long.
The prayer service at St Patrick’s Church of Ireland Cathedral has been organised by the four main churches to mark the formation of Northern Ireland and the partition of Ireland in 1921.
Church leaders expressed their sadness after learning the Queen would not be attending.
“We are very sorry to learn that it will not be possible for Her Majesty Queen Elizabeth II to be present for the Service of Reflection and Hope in Armagh tomorrow,” they said in a statement.
The statement was signed by Presbyterian moderator David Bruce, Church of Ireland primate John McDowell, Catholic primate Eamon Martin, president of the Irish Council of Churches Ivan Patterson and president of the Methodist Church in Ireland Sahr Yambasu.
“We wish to convey to Her Majesty our good wishes and, in doing so, to acknowledge the significance of her commitment to the work of peace and reconciliation, which has meant a great deal to people throughout this island.”