Awarded a Veitch Memorial Medal by the Royal Horticultural Society for her contribution to horticulture, Jean O'Neill and her husband, Terence O'Neill, moved to Glebe House in Northern Ireland in late 1945 or 1946. During her time in Northern Ireland, Lady O'Neill was instrumental in restoring the gardens at Rowallane, Mount Stewart and Castle Ward. Lady and Lord O'Neill returned to England after his resignation as Prime Minister in 1969.