He joined the
Labour Party in 1977 after moving to
Richmond. In 1978 he became the secretary of the Tasman electorate committee. A year later he became the secretary of the Tasman campaign committee. When Tasman MP, and former Labour leader,
Bill Rowling announced his retirement Shirley contested the nomination to replace him. From a field of seven (including
John Blincoe,
Annette King and
Stephen Rainbow) he was selected as Labour's candidate. Shirley first entered
Parliament in the
1984 election, when he stood as the
Labour Party candidate in the Tasman electorate. At the time, there was considerable tension in the
Labour Party over the policies of the
Minister of Finance,
Roger Douglas – the policies were based around economic
deregulation and
free trade, and traditionalists saw them as a betrayal of the party's
left-wing roots. Shirley aligned himself with the faction that supported Douglas. Shirley was not a member of the faction's so-called "Troika" (consisting of Douglas,
Richard Prebble, and
David Caygill), but was nevertheless a notable supporter of the reforms Douglas promoted.
Cabinet minister Eventually, the
Prime Minister,
David Lange, fired Douglas as
finance minister and then himself resigned. In the re-arrangement that followed, Shirley briefly held
Cabinet rank as
Minister of Fisheries, Associate Minister of Agriculture, Associate Minister of Forestry, and Associate Minister of Health. He lost these positions when the
Labour Party was defeated in the
1990 election. Shirley himself lost his Tasman seat to
National's
Nick Smith, leaving him outside
Parliament.
ACT New Zealand When Douglas and his allies created the
ACT New Zealand party, Shirley was involved. In
ACT's first electoral campaign, the
1996 election, Shirley was ranked in third place on the ACT
party list, and re-entered
Parliament as a
list MP. He has previously served as ACT's deputy leader, and in 2004, he was one of four candidates to seek the party's leadership after the retirement of
Richard Prebble. On the retirement of
Jonathan Hunt, he sought election as
Speaker of the House of Representatives, but placed third behind
Margaret Wilson and
Clem Simich. He remained a
list MP until the
2005 election, in which only two ACT MPs were returned. ==Post-parliamentary career==