Ireland is the European country with the most pro-Palestine support.

Because in the 17th century, the catholic Irish who lived in Ulster were forcibly evicted from their homes in order for them to be given to protestant Irish and English so the protestantism that dominated England could maintain a hold in what became Northern Ireland (an event which triggered all the Troubles that followed between Irish catholic Republicans and protestantant Unionists). You'll clearly see the perceived similarities between the two situations.