After his parliamentary career, he joined New Zealand First. Maxwell had a high profile as chairman of the Portage Licensing Trust, one of two Licensing Trusts in West Auckland. When Maxwell stood for Parliament in the Waitakere electorate in 1978 for the Labour Party, he was successful.
He represented the Waitakere electorate for three parliamentary terms, and when it was abolished for the 1987 election, he successfully stood in the Titirangi electorate instead.
In the 1990 election, he was defeated by Marie Hasler, one of a number of losses contributing to the fall of the Fourth Labour Government. Maxwell had a keen interest in agriculture and worked closely with Colin Moyle, who would become Minister of Agriculture in 1984.
Maxwell was the Associate Minister of External Relations and Trade and the Associate Minister of Agriculture in 1990. He had lost part of the support of his electoral team because his values had shifted away from Labour.
Maxwell moved from West Auckland to Otumoetai after he left parliament.
When New Zealand First was formed in 1993, Maxwell joined that party. He then moved to Paerata near Pukekohe where he worked in real estate. Maxwell died on 25 March 2012 aged 78.
In the 1995 New Year Honours, Maxwell was appointed a Member of the Order of the British Empire, for public services.