As member of Fianna FÃ il , he held a number of ministerial posts in the cabinets of Ã amon de Valera , SeÃ n Lemass and Jack Lynch , becoming TÃ naiste Deputy head of the government ) in 1969 . A member of Fianna FÃ il , he held a number of ministerial posts in the cabinets of Ã amon de Valera , SeÃ n Lemass and Jack Lynch , becoming TÃ naiste in 1969 .