Shortly before hosting nominees for the Australian of the Year awards at the annual garden party on the lawns of Yarralumla on Tuesday, Governor-General Sir Peter Cosgrove was receiving a smaller group of guests for an indoor ceremony that had been somewhat more recently arranged.

Prime Minister Malcolm Turnbull was there to see several of his ministers sworn in to new portfolios as part of a minimalist frontbench reshuffle sparked by the sudden resignation of Health Minister Sussan Ley over travel expenses.

Turnbull elevated West Australian MP Ken Wyatt to the posts of aged care and Indigenous health, making him the first Indigenous Australian to join the full federal ministry. Ley’s replacement in the senior health portfolio, Greg Hunt, welcomed the kangaroo-skin-clad Wyatt to the ministerial club with a giant hug.

But Wyatt’s entry in the history books at this particular juncture was a virtue born of an unhappy necessity.

Turnbull had been drafting plans for a different ministerial reshuffle much later, around the widely predicted future departure of Attorney-General George Brandis on a diplomatic posting.

Brandis has declined to confirm or deny that he will become Australia’s next high commissioner to London when the incumbent, former foreign minister Alexander Downer, finishes up this year.

But within both the ministry and the diplomatic community, Brandis’s future appointment is viewed as an open secret. His trip to London late last year prompted quips in foreign affairs circles that he was measuring the curtains.

The Saturday Paper has now confirmed that Brandis’s move abroad is expected in the second half of the year and that his replacement as attorney-general is likely to be West Australian former state attorney-general and treasurer, now federal social services minister, Christian Porter.

Neither position has been formally locked in yet.

Porter has made it known that he would like to become the top law officer if and when the job becomes available, and his strong performance in the more junior portfolio of social services has helped his cause.

Despite all the pre-Christmas speculation about the prime minister planning a refresh of his frontbench early in the new year, Turnbull had been planning to keep the existing line-up in place for a few more months. Then Sussan Ley hit the deck.

Instead of bringing forward his plans, he went for a bare-minimum change, filling only Ley’s vacancy and those positions that flowed directly from shifting former industry minister Hunt into her job.

A second reshuffle is still coming but not until midyear at the earliest, after the May federal budget.

That, too, is likely to be a limited rearrangement of faces to freshen up the Turnbull ministry as it heads into the second half of the electoral term. But senior government sources note the Ley episode was a reminder that plans can change on the basis of “things you don’t see coming”.

Turnbull is understood to be keen to maintain continuity through the budget process, which is getting under way as the political year begins.

Christian Porter has proved he can find savings and communicate the need for them effectively and Turnbull is believed to be asking him to do more of the same before he leaves the social services portfolio.

With the reshuffle date still not firm, there is also no fixed date for Brandis to pack his bags for Britain. The appointment is yet to go to cabinet.

It’s not clear whether it was Brandis or Turnbull who first suggested the high commissioner’s role, but it has become a mutually suitable opportunity for a senior figure who has also been slightly accident prone in recent years.

In the wake of the Brexit vote for Britain to leave the European Union, the job is being portrayed as taking on a different flavour and one well suited to Brandis’s skills.

Alexander Downer will wind up his posting over the next few months.

Some posts are routinely reserved for political appointees, with London and Washington, DC, foremost among them.

In those cases, prime ministerial selections are generally imposed on the foreign affairs minister, as was the case with both Downer and ambassador to the United States Joe Hockey.

Hockey’s predecessor, Kim Beazley, was appointed by prime minister Kevin Rudd but had his term extended under prime minister Tony Abbott.

Abbott was believed to have been keeping the job for his own special appointee – a move that never eventuated. Speculation at the time was that Turnbull would be offered the post, but the offer was never made. The other name that emerged subsequently was Abbott’s foreign affairs adviser, Andrew Shearer, an appointment that also never came to pass.

Shearer is now based in Washington with the Centre for Strategic and International Studies.

Ahead of the London changeover, the Department of Foreign Affairs and Trade is calling all Australian ambassadors and high commissioners home for a global heads-of-mission meeting in late March, the first time Australia has conducted such a summit.

They will spend two days in Canberra and two days in regional cities and towns around the country, and their discussions and feedback will feed in to the foreign policy white paper being drafted within the department.

Turnbull’s attention is more imminently focused on his own political year as he prepares to set out his 2017 agenda in a speech to the National Press Club this coming week.

With Opposition Leader Bill Shorten sneaking in his own address the day before, Turnbull is set to tackle the expectations many had upon his elevation to the prime ministership, including that he would legalise same-sex marriage and restore a carbon price within his first year of government.

“The prime minister will be using an address at the National Press Club to lay out his agenda and priorities for the year ahead, focusing on delivering for Australian households and businesses,” his spokesman told The Saturday Paper.

Those priorities are understood to include the issue that caused him such grief over the festive season – the overhaul of the parliamentary expenses system, including the long-foreshadowed abolition of gold travel passes and other recommendations made in previous reviews but never implemented fully.

In the wake of new US President Donald Trump’s withdrawal from the 12-nation Trans-Pacific Partnership free trade pact, Turnbull will seek to draw a distinction in the trade debate between the Coalition and Labor over who best supports Australian jobs.

Despite insisting it is Shorten and Labor playing politics on trade, that counter-campaign has already begun.

“Our position is very simple,” Turnbull said on Thursday.

“It’s not an ideological issue, it’s not a philosophical issue, it’s not even a political issue – other than the fact that the Labor Party remarkably now appears to be against trade. But we know that more opportunities for Australians to sell what they make, whether it is a physical good or an intellectual good or a service, mean more jobs in Australia. More trade means more jobs. That’s what we’re about.”

He said Australia needed to “remain very agile, focused on Australia’s interest” and not “throw in the towel on trade like Bill Shorten would do”.

Turnbull accuses Shorten of being pro-protection and therefore anti-trade. Shorten is running his own pro-jobs campaign – one that emphasises Turnbull’s personal wealth on the way through. That campaign is also already in full swing.

“Our plan for jobs is about building Australian, buying Australian, employing Australian,” Shorten said after Trump’s TPP move on Wednesday.

“As I travel around Australia talking and listening to Australians about jobs, my opposite number is in Canberra having a meltdown about the Trans-Pacific Partnership. I’ve got a suggestion for Mr Turnbull: stop worrying about what is never going to be and instead get out of the ivory tower, get out of the harbourside mansion, get out amongst the real people of Australia. Talk to real Australians who are having a go, listen to them about their idea for jobs.”

Shorten intends to run hard on jobs and continue the strategy that worked well for him in the election year: trying to get out in front of the government in laying out policy ideas.

Turnbull’s speech this week will emphasise moves to cut business tax and push on with stalled legislation for childcare assistance.

Also high on the priority list will be a proposed restructuring of schools funding and, with it, an overhaul of teaching standards to ensure that money spent is achieving results in education.

And in line with Treasurer Scott Morrison’s visit to Britain last week to examine moves to lower housing costs, the government is expected to bring forward a package of measures, possibly before the May budget, to address housing affordability and encourage the states and territories to take steps of their own.

Newly elevated New South Wales premier Gladys Berejiklian has also identified the issue as one of her highest priorities.

The federal government still favours supply-side measures and is understood to support the kind of step taken by the Australian Capital Territory’s Labor government, which is seeking to use a hike in land tax to force home owners to downsize and free up real estate.

But the federal moves will not include any change to negative gearing – the abolition of which is a Labor promise. On that, Turnbull is now steadfastly dug in.

Another major Turnbull government priority will be energy security, following summer blackouts across several states and the storms that knocked out power in South Australia late last year.

It has already commissioned a review of the security of the national electricity market and is undertaking a separate feasibility study into building a second electricity interconnector in Tasmania and further large-scale development of that state’s renewable energy resources.

Turnbull’s emphasis is likely to be on both reliability of supply and on reducing cost, conscious of the potential political benefits in being seen to address the volatile issue of household energy prices.

These leaders’ speeches will start the clock on the political year which, by convention, begins officially after Australia Day.

Despite a less-than-carefree summer, punctuated by the Ley expenses drama and an automated overbilling system in Centrelink, Turnbull is upbeat.

Not even the first opinion poll of the political year, published this week by Essential Media, has dented his mood.

The poll has the Coalition’s primary vote at 35 per cent – down a further 2 percentage points since Christmas and 7 since last July’s election, when it was at 42. Labor’s is steady at 37 per cent, but up 2.3 points on July.

Mysteriously, the percentage of voters willing to invest some kind of trust in parliament has nudged up 4 percentage points in the past four months, to 30 per cent.

But the message is mixed. Although trust in political parties is up slightly, too, it’s lingering at just 17 per cent.

On that basis, the end of the holiday season should not see any of them too relaxed or comfortable.