1920–21 season
... that by winning promotion during the 1920–21 season, Cardiff City F.C. became the first Welsh club to reach the top tier of English football?
... that by winning promotion during the <b id="mwBAg"><a href="./1920–21_Cardiff_City_F.C._season" id="mwBAk" rel="mw:WikiLink" title="1920–21 Cardiff City F.C. season">1920–21 season</a></b>, <a href="./Cardiff_City_F.C." id="mwBAo" rel="mw:WikiLink" title="Cardiff City F.C.">Cardiff City F.C.</a> became the first Welsh club to reach the top tier of English football?