Elworthy was the leader of the Federated Farms of New Zealand during the reforms in the 1980s. In 1987 he received the Bledisloe award for agriculture.
One of Elworthy's major accomplishments was the takeover of New Zealand's largest farming/fertiliser company "Kempthorne Prosser & Co. Ltd" which was absorbed into Ravensdown Fertiliser Co-operative. His business interests were equally strong, from being instrumental in the founding of the Ravensdown fertiliser co-operative (1977–1982) to his association with Auckland's highly successful Sky City casino as a director. He was knighted in the 1988 Queen's Birthday Honours for services to agriculture. He was a member of the Institute of Directors.
Elworthy owned a Tiger Moth aeroplane which he used to fly around New Zealand.
In January 2004, Elworthy died suddenly of a heart attack early in the morning on the way to the bathroom.
He is survived by his wife Fiona Elworthy, 2 sons (Forbes and Charles) and 2 daughters(Josephine and Eve).