In 1977, Petch was elected to Ryde Municipal Council, and from 1980–87 he also sat on Sydney County Council, of which he was chairman in 1984 and 1985. From 1984–87 he was an executive member of the Local Government Association. He was active in the Ryde local area as Chairman of the Ryde "Red Cross Calling" Appeal 1978–84, President of the Ryde Lions Club 1985–86, and honorary member of the North Ryde Rotary Club, from which he received a Paul Harris Fellow award. He was also appointed a Knight of the Order of St Lazarus of Jerusalem.
