At first, Birch stood in Franklin,[3] succeeding the retiring National Party MP and Speaker of the New Zealand House of Representatives Alf Allen.

Over Birch's career, the extreme borders of his electorate sometimes extended as far as north as Beachlands, as far west as Pirongia Mountain and as far east as Thames (though never all at once).

In response the Polynesian Panthers activist group staged "counter raids" on the homes of Birch and the Minister of Immigration Frank Gill, surrounding them with light and chanting with megaphones.

[11] As Minister for National Development, Birch was closely involved in the Think Big project, a series of high-cost programmes designed to reduce New Zealand's dependence on imported fuel.

[13] McLay later dumped Birch as finance spokesman in an attempt to "rejuvenate" the party and instead allocated him the job of spokesperson for Labour and Employment and the twelfth rank.

[15] Under new leader Jim Bolger, Birch returned to his position as third-ranked in caucus and retained the Labour and Employment portfolios.

The Prime Minister, Jim Bolger, had never been a supporter of Richardson's strong laissez-faire policies, and preferred the more conservative Birch for the Finance portfolio.

New Zealand First's leader, Winston Peters, insisted on control of the Finance role as part of the coalition agreement, and National eventually agreed.

Mike Moore of the Labour Party commented that "we are always impressed when Winston Peters answers questions, because Bill Birch's lips do not move.

For a short period he held both financial offices until Bill English was promoted to be Minister of Finance, leaving Birch with the senior role.

[1] In the 1999 Queen's Birthday Honours, he was appointed a Knight Grand Companion of the New Zealand Order of Merit, for public services as a Member of Parliament and Minister of the Crown.