Wow ..... You REALLY went to the wrong pub. The most welcoming bars I've been to in two decades of business travel were in the Irish countryside. (Close second is the Netherlands - Amsterdam and Eindhoven.)
Yes, the Irish enmity toward the English is still widespread but in the Republic it's a mile wide and a foot deep as more than one Dubliner has told me. By this they meant that they hadn't forgotten but they are inevitably and perhaps, tragically, drawn together by their common heritage. Man United is the most popular team in Ireland, Rugby weekends in Dublin are the best night out of the year and most Irish families have relatives living in London and visit frequently. The relative prosperity in the Republic of Ireland over the past 30 years has blunted the painful edge of old wounds. Many Dubliners believed living well was the best revenge.
Not so in the North. Visit Derry, Belfast or Port a Down if you want to see the old embers waiting to flame again. There the Catholic schoolchildren are still reminded yearly that Ireland was a net exporter of food during the great famine - English landlords sold their produce in London while a million of their Irish neighbors starved to death. Of course in these cities you don't need to go all the way back to the potato famine to find an insult. The"Troubles" are in everyone's recent memory, in some neighborhoods the IRA murals are freshly painted and one friend showed me rubber bullets he'd collected in his neighborhood during a June marching season.
When visiting it's best to remember that to us (and the band) the famine is century's old news - In places on that island its presence is still palpable.
Here's a picture of the famine memorial mentioned above. It's on the Northside quays of the Liffey as you approach the docks. Haunting.