From 1984 to 1992, Eng worked full-time as chairman of the Norwegian Association of Local and Regional Authorities. He had become involved there as a member of the wages committee from 1976 to 1980. Also, he had been a member of the organization's central committee from 1980, and remained so until 2000.[2] As leader he replaced Sverre Krogh, who received decisive support from the Christian Democratic and Conservative parties—at the time coalition partners with Krogh's Centre Party in Willoch's Second Cabinet.[5]
Through the Norwegian Association of Local and Regional Authorities, Eng became involved in international work. He was a board member of the International Union of Local Authorities (IULA) from 1984 to 1992, and of the International Council of Environmental Initiatives (ICLES) from 1990 to 1998. In the Council of Europe he was a part of the Committee on Regional Problems and Regional Planning from 1980 to 1984, the Conference of Local and Regional Authorities of Europe from 1980 to 2000, the Committee on Environment and Town Planning from 1984 to 1988 and the Standing Committee from 1989 to 1992.[2]
He was also involved in the Norwegian Lutheran Mission and the local parish council. He also held many other memberships in municipal and regional boards and committees, as well as in local enterprises.[2] He lived in Skudeneshavn.[6]