In official documents released earlier this month it appears the Queen of England used the wrong name for the Republic of Ireland when writing to president Patrick Hillery.
State papers released under the 30-year rule reveal a glaring error picked up by a senior civil servant and adviser on presidential affairs.
In extravagantly worded letters to President Hillery in 1983, the British monarch marked the changing of the ambassadorial guard in Dublin.
In the note personally signed by the Queen, the royal confirmed the departure of Sir Leonard Clifford William Figg and in a follow-up note his replacement is confirmed as Alan Clowes-Goodison.
However an error was spotted in the correspondence. Despite the courtly language and tone of the diplomatic letters to President Hillery, the Queen had used "Irish Republic" rather than Republic of Ireland.
"We are Ourselves so satisfied with the zeal, ability, and fidelity with which Sir Leonard Figg has executed Our orders on all occasions during his Mission that We trust his conduct will also have merited Your approbation, and in this pleasing confidence We avail Ourselves of the opportunity to renew to You the assurances of Our constant friendship, and of Our earnest wishes for the welfare and prosperity of the Irish Republic," she wrote, according to the Irish Independent.
The 1948 Republic of Ireland Act, when the country formally became a republic with the president as head of state, declared that the state should be referred to as the Republic of Ireland.
The government secretariat twice raised concerns over the misnomer, but there is no reference in the file as to whether Irish representatives wrote to Buckingham Palace or Downing Street over the error or whether it was resolved.
An embarrassing error to come to light with the impending visit of Irish President Michael D Higgins approaching. In April President Higgins will make the first official state visit to the UK by the Irish head of state.
The Queen formally invited the President and his wife Sabina to stay with the royals at Windsor Castle next April 8.
Aras an Uachtarain - the President's official residence in Dublin - confirmed they have accepted the invitation.
The groundbreaking three-day State visit follows the Queen's hugely successful trip to Ireland in May 2011.
The strange history of the Nazi plans to invade Ireland