His Barnaby Joyce problem shows once again that maintaining the Liberal-National coalition comes at an enormous cost and it is an arrangement which deserves far greater attention and transparency. Instead it is clouded in secrecy and taken for granted. The Coalition, which commentator Peter Brent correctly describes as a strange beast, is more often than not treated as a single party in which the Nationals are a sort of rural outlier, like a Labor Party faction, rather than a fully-fledged separate political party.

But even given some similarities to a faction (dictating who their ministers will be, for instance) and given the fact that in Queensland the two parties are actually one Liberal National Party, the Nationals are very much a separate entity.

The two parties are usually described as senior and junior partners in the Coalition. The arrangement is sometimes described as a marriage, which seems strangely apt in the present circumstances, even if it is a marriage of convenience in which there are no alternative suitors.

But even in an age of marriage breakdown the term marriage has never fully captured the flavour of the relationship between the Liberals and the Nationals. Instead the Coalition is a strictly business relationship struck between two exceptionally hard-headed organisations whose business is politics and whose aim is election victory and then government.

History shows this and so do the descriptions used by the participants to describe their contractual relationship. On both sides there is suspicion and condescension. Heaven knows how the Liberal National Party works.

What brings the parties together is the same thing as in any business deal. Each side has something that the other wants and which can only be achieved by working together. The Liberals need the Nationals to form a parliamentary majority. There are no other realistic options. The Nationals need the Liberals to gain entrée to government. The Liberals won't risk minority government by standing alone, while the Nationals won't risk losing the perquisites of office. They want to be inside the tent.

The Coalition is only maintained by stringent non-competition rules for sitting members which rule out three cornered contests in which both Liberals and Nationals stand against Labor, leaving it to the voters to decide. Instead the voters' choice is seriously limited.

These efforts to eliminate competition also lead to cumbersome joint Senate tickets of the sort which produced the Fiona Nash-Hollie Hughes-Jim Molan fiasco. Liberal and National voter choice is sacrificed to avoid competition between the two parties.

Even then the precise governing contract is negotiated in private between the two leaders whenever a government is formed or whenever a party leader changes. This happened when Turnbull replaced Tony Abbott in 2015 and again in 2016 after the federal election. The Nationals have always driven a hard bargain. Back in December 1967 after Harold Holt's demise they even refused to serve under Billy McMahon and John Gorton became prime minister.

The public aspects of the bargain are the division of ministerial portfolios according to the number of seats each party holds and the gift of the deputy prime minister's position to the Nationals leader. If the Nationals ever became the larger party as Joh Bjelke-Petersen hoped to achieve in 1987 the Nationals would take the prime ministership.

The private aspects of the bargain, never published, are the agreements made behind closed doors, such as the concessions demanded by the Nationals and agreed to by Turnbull when he became prime minister. These included no change to same sex marriage policy and to Nationals' control of water policy.

Even given all these concessional arrangements the Nationals have always felt free to attack the Liberals without fear of retribution. Backbenchers, such as Andrew Broad, MP for Mallee, attacked Turnbull for a "complete lack of leadership" during the same sex marriage postal survey campaign. George Christensen, MP for Dawson, threatened to bring down the government over a banking royal commission and constantly acts erratically without being called to account. John Barilaro, Nationals' Deputy Premier of New South Wales, called on Turnbull to resign recently because he was out of touch.

Nationals' leaders strive for an independent rural identity, hence Joyce's symbolic Akubra hat. Nationals' members and voters applaud any sign of independent behaviour, no matter how outrageous or silly, even to the extent of supporting ex-Nationals like Bob Katter.

All this is the background to the position Turnbull found himself in when Joyce's perilous personal situation became public. Coalition government weakens the power and control of the Liberal Prime Minister. It was that weakness which led to Turnbull engaging in megaphone diplomacy with his deputy rather than trying to assert his authority privately.

Turnbull's job would be made much more straightforward in dealing with recalcitrant ministers and backbenchers if he was the leader of a single party, though the Labor experience shows that dealing with factions can still be fraught with difficulty.

Nevertheless, that doesn't mean that the parliament would be better off without the Nationals. There is another side to the story.

We need more political parties rather than fewer. The parliament is more diverse and certainly more colourful because of the existence of the Nationals. Increasing the range of political parties contributes to greater diversity of thinking and a greater variety of philosophical views. That makes Parliament and government messier, as it certainly is now, but we are ultimately better off.

John Warhurst is an emeritus professor of political science at the Australian National University.