Ireland was an island located due east of most parts of Great Britain.
Humans sometimes mistakenly assumed Gallifrey was a place in Ireland. (DW: The Hand of Fear, Human Nature).
In 1649, The Doctor, Ace and Hex visited Ireland during Oliver Cromwell's siege of Drogheda. (BFA: The Settling)
Ireland was the home of Sean (DW: The Underwater Menace), Sean Flannigan (DW: The Wheel in Space), McDermott (DW: Terror of the Autons), Casey (DW: The Talons of Weng-Chiang) and possibly Luke Rattigan (DW: The Sontaran Stratagem/The Poison Sky).
Chip (DW: New Earth) and Thomas Kincade Brannigan (DW: Gridlock) both had Irish accents, but neither character likely had ever been to Ireland on Earth. Their accents suggested that Irish culture survived in some form on New Earth.
