Gleeson has character, reputation and capacity. He is steeped in administrative and constitutional law, and, if not political, has not had visited on himself the maledictions of conservatives sick of liberal or creative judges. He is steady, cautious, methodical and wise. He is up to the ceremonial functions and visitations now obligatory for vice-regal office, but has never manifested any desire to play to the crowd. He is very witty, but does not play to the gallery: some of his more recondite jokes could bring on climate change.

His nickname - ''Smiler'' - is a joke about a deceptively funereal expression. An teasing colleague from the NSW Court of Appeal, Roderick Meagher, once wrote: ''He has written nothing outside his professional work. He takes no interest in either music or art. He does, however, like flowers. He stares at them to make them wilt.''

Once there was a possibility that it might not be Gleeson, but a colleague from both the NSW Court of Appeal and the High Court, Michael Kirby. Though Kirby is personally liberal, he is a longtime close friend of Abbott, and they worked together as monarchists to oppose a republic for Australia. Friends of Abbott have also thought that putting Kirby and his partner Johan van Vloten at Yarralumla might disarm those led to assume that Abbott was hostile to or judgmental about homosexuals, as well as generally wrongfoot those whose constant claim is that he has a secret moral agenda.

Kirby would grace the office, and inject his own interests and concerns into the performance of his duties. But advisers close to Abbott's ear would worry whether he would be ''sound'' on issues of constitutional principle: Kirby might be a monarchist, but was ever radical and adventurous - and often in dissent with his colleagues - as a judge. And on some issues that could be sensitive for government, perhaps particularly on human rights and Aboriginal affairs. One could never be certain that he was a ''government man'', let alone a person with instinctive sympathy with conservative ideas.

The fear with Cosgrove is not about his going native, or of his using the office to push an agenda. Nor is there any doubt about his capacity to play chief citizen, chief mourner or motivator in chief. It is that he would be essentially out of his depth and somewhat unpredictable in a serious constitutional crisis - perhaps the more so if he perceived some need (as Sir John Kerr did in 1975) to be seen as independent of, and no mere cypher of the government of the day.

Cosgrove has had excellent personal public relations through his military career, which ended as chief of the defence force. He did excellent work for Australia in East Timor. But many of his colleagues, civil and military, think he was promoted past his abilities in being made head of the army then CDF. He has been said to have lacked the application, depth and political and administrative skills for higher defence policy; some of the results of this will be becoming more evident over the next governor-general's term.

No one can yet say what problems will move from the cabinet rooms in Barton to Yarralumla, or when or how they will. But they will involve relations between the House of Representatives (which is to say the government) and the Senate, whether before it changes in composition on July 1, or after. Also at risk of becoming involved is the practical administration of legislation Abbott does not want but which he cannot repeal.

Abbott lacks a Senate majority to carry out his campaign promise to abolish the carbon and mining taxes. He may not even have the time to create the circumstances by which he can ask the governor-general for a double dissolution

before then, given ways the Senate can delay a vote for a period.

Initially, Abbott, confident that the electorate supported his policy of repealing the taxes, spoke brusquely of a double dissolution if the Senate failed to accept his mandate. More likely, however, he was confident that the Senate formed on July 1, to meet first in August, would have the numbers to pass his repeal bills.

Now, however, that is by no means as certain, at least while the half-Senate result in Western Australia is in doubt. Nor is it clear that a double dissolution would improve his position.

If the Court of Disputed Returns orders a fresh state Senate election, Abbott may be down one or two on the Senate votes he needs. That problem could continue through the rest of his term.

Just as significant, however, is the impact this has on the Hockey budget in May. One can expect or assume that the budget will assume that carbon and mining taxes will not be in effect after July 1. But, unless the Senate agrees to such a repeal, the government will be obliged to continue collecting them, whether it wants to or not.

There have been times in constitutional history when executive governments have not liked laws imposed upon them by parliaments. Some kings, such as James II in the 1680s, attempted to deal with that problem by executing only the laws he agreed with. That cost him the throne, and caused the Glorious Revolution of 1689 when Parliament deposed the king, passed the throne not to the heir apparent but to his daughter and her husband, and adopted the Bill of Rights as a limitation on the rights of future kings or ministers.

Among the rights and freedoms declared by the Bill of Rights – still a part of our fundamental law – are that ‘‘the pretended power of suspending the laws or the execution of laws by regal authority (for which read ministers) without consent of Parliament is illegal’’; and ‘‘the pretended power of dispensing with laws or the execution of laws by regal authority, as it hath been assumed and exercised of late, is illegal’’.

Scholars still differ about some residual power of dispensation. But no king or ministry has dared to explore if it gives room to manoeuvre.

Abbott cannot know now his game plan. But if thinking ahead, he needs to be sure of the umpire. He wouldn’t want anyone doing a Kerr or a Ninian Stephen on him.