Politicians can make very good ambassadors. But when too many former politicians are on the diplomatic circuit, there is a cost to good diplomacy — a problem that Australia must now confront.

Both Coalition and Labor governments have a long history of dispatching former ministers or MPs to represent the nation overseas. But a record has been achieved during the Abbott-Turnbull-Morrison years. In the Abbott era, the ratio of political appointments versus career diplomats in top diplomatic jobs was the highest in Australia's modern history — at one stage, roughly one in ten.

More are being announced. Foreign Minister Marise Payne at the weekend made her friend and former NSW Liberal, Patricia Forsythe, Australia's representative in Wellington. A few weeks back, Liberal ex-senator David Bushby was winging his way to be consul-general in Chicago.

They join the ranks of former attorney-general George Brandis, camped in London as High Commissioner, and former treasurer Joe Hockey, Australia's man in Washington. There are others too, with names less recognisable.

Are tribal politics dictating appointments?

Before, these former politicians were allowed to serve their term overseas regardless of a change of government back home. But this truce seems to have unravelled. In 2013, the Coalition torched plans to send former Victorian Labor premier Steve Bracks to a consul role in New York. In Labor ranks, this was seen as an act of petty partisanship, compounded when former Liberal senator Nick Minchin snared the job instead.

Now, it appears payback is on the way. A report on Monday claimed up to six former Coalition MPs appointed high commissioners, ambassadors or consuls could face the chop should Labor win the next election.

These postings abroad are described by the media as "plum" — a cosy retirement gig on the taxpayer's purse.

But there can also be a benefit to political appointments. Diplomats often have foreign language skills, but in a heady political town like Washington, it can help to have a representative who speaks "politician", with strong connections to the government back home. In a diplomatic relationship, the other side wants to know its messages are being heard.

If Joe Hockey picks up the phone, Scott Morrison will answer.

But this is where the problem becomes clear. Relationships are predicated on trust. If Bill Shorten sits in the Prime Minister's office rather than Mr Morrison, will the Labor leader listen to Hockey's advice?

Australia has encountered this problem before. Tony Abbott inherited former Labor leader Kim Beazley as Washington ambassador. The Coalition made the deliberate choice to extend Mr Beazley's term, to signal to Barack Obama's White House that Mr Beazley still had the ear of Canberra.

Kim Beazley (right) with then US Secretary of State John Kerry was appointed Australia's Ambassador to the US after retiring from politics. ( Reuters: Peter Parkes )

Likewise, in 2007, Kevin Rudd was under pressure to recall then newly appointed ambassador to Italy Amanda Vanstone, but in keeping with past practice, allowed her to serve out her term.

Yet Mr Rudd won no favours. In 2016, Malcolm Turnbull refused to back his bid to be UN chief. Rudd was a polarising figure, but as prime minister he had supported former rival Alexander Downer to a UN special envoy role in the Cyprus conflict, and made a point (to some annoyance within Labor) of sending former Coalition MPs abroad, such as Tim Fischer to the Vatican and Brendan Nelson to Brussels.

So what can we do?

Given the rate of political appointments, Australia might be wise to borrow America's tradition of congressional hearings before an ambassador is confirmed to a post.

This would essentially be a competency test: if held by a parliamentary committee, it would allow both Coalition and Labor members to quiz a would-be top diplomatic envoy.

Australia should adopt confirmation-style hearings not just for former politicians but all head of mission positions. Open hearings would escape the opaque manner in which these jobs are given, and assess other appropriate candidates who might be drawn from areas of government outside the Foreign Affairs portfolio, or from the business community, or state government.

The cunning old saying was that an "ambassador is an honest gentleman, sent to lie abroad for the good of his country". Seeing the right man or woman in the job, capitalising on their experience, connections and knowledge, should be the test for Australian diplomacy.

Daniel Flitton is managing editor of the Lowy Institute's Interpreter blog, where this piece first appeared.