Former National Party chief of staff Wayne Eagleson has signed up with political consulting firm Thompson Lewis.

Top political advisers from opposite sides of the political divide have joined forces.

Former National chief of staff Wayne Eagleson has taken a job with political consulting firm Thompson Lewis, which is run by former acting Labour chief of staff GJ Thompson.

Eagleson, who was chief of staff to both John Key and Bill English from 2008 until 2017, quit the National Party just days after last year's election.

SUPPLIED (Left to right): Caddy Brett Smith, Paraparaumu Beach Golf Club general manager Leo Barber, former prime minister John Key, club president Paul De Bernardo and Wayne Eagleson (right) play a round of golf the day before Key's resignation.

However, he stayed around after announcing his resignation to help the party through coalition negotiations.

READ MORE:

* National Party's most senior adviser resigns

* Labour chief of staff Neale Jones takes up job with lobby firm Hawker Britton

* English hires Key's chief of staff Eagleson in sign of 'continuity'

Prior to his chief of staff role, he worked in the office of the leader of the Opposition, and also worked as a private secretary to former prime minister Jim Bolger in the 1990s.

Eagleson was a pivotal figure in the former National government and was once described by Key as New Zealand's "most influential unelected official".

He was often said to be the one running the country when Key was out of town."When Eagleson says it, Key says it," many an insider had been known to say, and the MPs believed it too.

Eagleson's attributes of being calm and unflappable were seen as contributing to the Key government's success.

​Outside of Parliament, he worked as a member of the senior executive team for Transpower, and in senior roles for Westpac and DB Breweries.

In 2010, Eagleson's trip to Las Vegas with a group of lobbyists made headlines after Key had explicitly discouraged his ministers from publicly fraternising with lobbyists, but the trip happened during Eagleson's annual leave, which was approved by the prime minister, and was funded out of Eagleson's own pocket.

Eagleson was described as a Wellington-based consulting partner of Thompson Lewis on the firm's website.

He also worked with a number of personal clients on a range of projects in both New Zealand and Australia, it said.

As well as being a consulting partner for Thompson Lewis, Eagleson is the sole director and shareholder of Wayne Eagleson Consulting - a company he set up at the end of last year.

The news of Eagleson's appointment came as firm director and founder Thompson finished a four-month stint as Prime Minister Jacinda Ardern's acting chief of staff, while chief of staff Mike Munro was recovering from illness.

Thompson - an Aucklander and former journalist - worked as press secretary to former prime minister Helen Clark, and as chief adviser and chief of staff for the leader of the opposition.

He was brought on by Ardern to assist the new government's transition into the Beehive.

Thompson said he, and the other directors, knew Eagleson well, and knew he had a depth of experience and knowledge of how New Zealand politics worked.

It was also good to have someone on board who had come from the other side of the political divide, Thompson said.

"In New Zealand, you can't afford to be too partisan."

Thompson left his lobbying job to help set up the new government, before returning to his life in Auckland, meaning he has up-to-date knowledge of and contacts within government. Eagleson has the same advantage with the National Party.

Some other countries impose a "cooling off period" on MPs and political advisers, who wish to move from Parliament to lobbying. New Zealand does not have these regulations, which gives MPs and advisers the freedom to move between jobs.

Thompson said his knowledge and relationships with politicians had been built over the past 20 years of his career, and the past four months were not "make or break". Work in government relations was dependant on depth of knowledge and longstanding connections.

The firm's deal with Eagleson was done "over a couple of beers".

Thompson Lewis' other named director, David Lewis, also had a background in the top echelons of government, working as Clark's chief press secretary.

According to the firm's website, Lewis had advised on a number of successful central government and Auckland mayoral campaigns.

The move by lobbying firms to cover both sides of the political spectrum in New Zealand was kicked off last year after Hawker Britton - the left-wing sister firm of right-wing firm Barton Deakin - returned to set up shop in New Zealand, following a hiatus during the term of the last National government.