Complex sentence: There was little mainstream political interest in Home Rule following the First World War, and the focus of Welsh nationalist politics moved to the newly-founded Plaid Cymru from 1925, although it took until the late 1960s for Plaid to make its first electoral breakthroughs.
Split into simpler sentences: There was little mainstream political interest in Home Rule following the First World War. The focus of Welsh nationalist politics moved to the newly-founded Plaid Cymru from 1925, although it took until the late 1960s for Plaid to make its first electoral breakthroughs.