 In 1971 he won his first Leinster title, however, in spite of an outstanding display by Eddie Keher, Kilkenny lost to Tipperary in the All-Ireland final.In 1972 Larkin won a second Leinster title before helping Kilkenny to defeat Cork in the subsequent final to win his first All-Ireland medal.1973 saw O'Brien win another Leinster medal, however, Kilkenny were defeated by Limerick in the All-Ireland final.