[2] Neilson joined the Labour Party in 1972 and stood for the Auckland Regional Authority in the 1974 local elections on a Labour ticket alongside future parliamentary colleagues Helen Clark and Richard Northey.

[6] He became chairman of a convenor and secretary of a caucus economic committee and tasked with finding methods to leave the then current wage and price freeze in New Zealand.

[2] To commemorate the 50th anniversary of the construction of New Zealand's first state house located in the Miramar electorate, Neilson and Minister of Housing, Helen Clark, carried a coffee table through the same door that former Prime Minister Michael Joseph Savage had done 50 years before.

[7] In 1984 Neilson was appointed a Parliamentary Under-Secretary to Minister of Trade and Industry during Fourth Labour Government of New Zealand.

He undertook several overseas commissions for Ernst & Young before leaving to become Chief Executive Officer of the Sustainable Business Network.