He was a Liberal member of the Victorian Legislative Assembly, representing the seats of Gippsland West (1970–76), Berwick (1976–92) and Pakenham (1992–2002).
He worked in the Victorian Attorney-General's department before teaching at Sunshine and Northcote High Schools, finally becoming a farmer in South Gippsland at San Remo jointly with his brother.
He was opposed to local control of planning matters deemed to be of strategic importance of the economic growth of the State.
[3] In Crikey, Stephen Rowley wrote of his role as Planning Minister: "Maclellan was notoriously and unapologetically interventionist, and despite the ultimate fate of the Kennett government, his "can-do" attitude mostly benefited him politically".
[1] Maclellan was made a Member of the Order of Australia (AM), 2005, "For service to the Victorian Parliament, particularly in the areas of planning and transport, and to the community.
"[5] In late 2011, Maclellan was identified as having made several personal requests to the sitting Victorian Planning Minister Matthew Guy to support rezoning of farmland at Ventnor on Phillip Island, that a family friend needed to make a possible housing development viable.