President Joe Biden’s paternal surname was brought to the United States in the early 19th century by one William Biden, a stonemason who emigrated to Maryland from the village of Westbourne, in southern England. As far as anyone knows, Mr Biden has yet to visit. But this week he made his third pilgrimage in seven years to Ireland, the homeland of his maternal ancestors: the Blewitts of Mayo, and the Finnegans from Louth. He made the first of these visits, in 2016, as vice-president; the second a year later as a private citizen; and the latest, triumphantly, as president. He has been showered with shamrock wherever he goes.