Former Treasury official and one-time Labor Party member David Hughes heads Alistair Coe's team

Mr Hughes is a critic of Labor's Gungahlin tramline, having once been in charge of major project assessment for ACT Treasury.

Chief Minister Andrew Barr also has a new chief of staff, with the departure of Jamie Driscoll and his replacement by former deputy chief of staff Michael Cook.

Mr Hughes has written frequently on the light rail project over the past two years, insisting that it must stack up on transport terms and criticising the business case for its inclusion of much wider benefits.

While Mr Hughes, an economist and former academic, was a member of the Labor Party and president of a Canberra south branch in the 1980s, he has also worked on the staff of federal Liberals Julie Bishop, Joe Hockey, Malcolm Turnbull and Tony Abbott.

He also worked on one of the ACT's biggest political scandals – the Carnell Liberal government's redevelopment of Bruce Stadium. Mr Hughes was on the team in the auditor-general's office which investigated the project. The audit began as an investigation into the government's overnight loan at the end of a financial year to cover an over-spend, which had the effect of turning an over-spend into borrowing in the annual accounts. But it ballooned into a wider audit, with Mr Hughes focusing on the economic analysis.

"The key error of major projects is not doing sound analysis upfront, and making decisions based on the best available evidence," he said. "Often projects go wrong because they start off on the wrong foot or they start at all."

After the Bruce Stadium audit, Treasury boosted its ability to analyse major projects by taking on Mr Hughes.

He has now emerged from semi-retirement to head the Liberal staff.

Asked why he had accepted the job, Mr Hughes, 57, said: "I believe in good government and good government requires consideration of the evidence and approaching things in an open way. Philosophically, I'm a Liberal. I do believe in the values of individual effort within the law."

He doesn't belong to the party but said he would join, not because of any "tribal" affiliation but because he "probably should" as chief of staff.

While Mr Hughes adds considerable strength to the Liberals' economic hand, the Liberals' election loss probably owed more to Labor's more sophisticated and targeted campaign with swinging voters.

Mr Coe said Mr Hughes' appointment was just one part of the Liberal strategy.

"At the end of the day there's a heap of boxes that need to be ticked and collectively we need to make sure that they're all checked," he said.

"David's not on board because of the particular views he has. He's on board because of the experience and expertise that he can bring. We need to have an analytical approach to how we develop policy and how we actually operate as an opposition and that's the rigour that David will bring."

Mr Hughes' insistence that the light rail project should stack up in transport terms will also complicate any shift by the Liberals towards supporting the second leg of the tramline to Woden. The transport benefits for the Gungahlin line are marginal, and the Woden line might well struggle more on that score, given the cost of crossing the lake, the complications of developing land along Adelaide Avenue and the development focus on Northbourne Avenue. But politically, the Liberals will find it difficult to oppose the Woden leg.

Mr Barr's new chief of staff was a former deputy chief of staff to former federal attorney-general Mark Dreyfus and to Nicola Roxon, and before that worked for the Northern Territory Labor government. He joined Mr Barr's staff in January 2015.

Mr Barr's new deputy chief of staff is Mark Nelson, who resigned as president of the Labor Club board to take up the job.

Two Labor candidates have also been given jobs in the parliamentary team, with Angie Drake and Josh Ceramidas both joining deputy chief minister Yvette Berry's staff.