When the story of the Rudd-Gillard Labor governments is told Wayne Swan will be seen as a quiet achiever. Nothing special was expected of him back in 2007. He was generally assessed as a weakness in the new government. Opposed by the high-flying shadow treasurer and leadership aspirant Malcolm Turnbull he was expected to be mincemeat.

Following two of the great treasurers in Australian political history, Peter Costello and Paul Keating, he was very much in the shade and, it seemed, fighting in a different league. Yet after five years he hasn't been the weak-link in the Labor government. Instead he has battled on.

He hasn't been touted as a possible Labor leader unlike half of the cabinet. He hasn't had a tilt at the leadership as his opponents Turnbull and Joe Hockey have. He hasn't picked up his bat and ball and gone home like former finance minister Lindsay Tanner did in 2010. He has persevered when others have not. First he was Rudd's less-important Nambour High offsider. Then he was elevated to Deputy Prime Minister under Julia Gillard.

There has been no hint of scandal, which is to his credit. Queensland Labor is hardly squeaky clean. Though he did have a bit part in the Godwin Grech affair in denying anything untoward in the way claims for assistance by car firms were processed by the Treasury.

Swan is a man of limited public skills. His background as an academic and party machine man shows up in a somewhat grey public image. The government could have done with more flair in his position as it struggled to communicate its message to the public. Tanner definitely was more assured and confident with the Parliament and the public. Swan tends to bluster and is not as cool under pressure as Tanner's successor Penny Wong.

But he has been humanised over the journey. First there was his successful battle with prostate cancer, followed by his public campaign against the disease. Then there was his pent-up explosion of invective against Rudd during the second Rudd-Gillard leadership contest.

He broke into print (he had previously authored a well-regarded book about poverty called Postcode) in The Monthly magazine taking on billionaire miners, one of whom, Clive Palmer, has just announced that he will stand against him in Lilley at the next election.

The position of treasurer is an unusual one in Australian politics. The treasurer is responsible for the presentation of the government's budget and a great deal of fuss is made over that role, especially during the day on which it is presented. All the focus is on the treasurer and the fiction is maintained that it is their work alone. The treasurer is almost represented as an individual apart from the government. In fact, it is the government's budget.

Yet during this one week of the year the treasurer, rather than the prime minister, is pitted against the leader of the opposition. Really, the shadow treasurer should be given the responsibility of responding. It is a most unusual arrangement, though the PM is equally responsible for selling the budget.

The treasurer-prime minister relationship is an unusual one, especially at this time. The relationship can be very tense as the PM is the head of government and used to imposing their will and getting their way. Treasurers don't always get their way, though they bear responsibility. Treasurers want control and even if they don't, the department they represent, the Treasury, certainly does. Recent history is full of tensions, not just because of leadership conflict. This tension is one of the sub-themes in The Australian Moment, the recent book by George Megalogenis.

The contested role of a powerful government department can't be avoided. Part of the story is of influential Treasury heads of department and of a department so regarded that it was split in two by the Fraser government into Treasury and Finance in an attempt to break that power. Governments fear Treasury more than any other department, yet they must rely upon it. And it must be said that Treasury predictions have let down governments by being wrong at key points over the past 40 years.

You can read The Australian Moment to be reminded of the tensions between Malcolm Fraser and John Howard, Paul Keating and Bob Hawke and finally John Howard and Peter Costello. In most cases it is a story of the prime minister riding roughshod over the treasurer. Bitterness ensued because the treasurers believed that their correct economic priorities were overturned by political priorities. It is both a positive and negative measure of Swan that he is rarely seen in this light. There are few stories of Gillard-Swan tensions over economic policy. This budget is being sold by Swan, Gillard and Wong together.

Great treasurers are great communicators. Swan will not be remembered as a great treasurer because he is not up with the best in this regard despite growing in confidence over the past five years. If he was, the government's economic achievements may be held in greater regard. But that defect is certainly not just Swan's fault. Prime ministers and senior cabinet ministers also bear that responsibility. There may even be deeper aspects of the self-deprecating Australian psyche that militate against acceptance that Australia is an economic success story. Australians tend to laugh at overseas plaudits for our treasurers.

Swan has held up his end. He has made the most of the raw material he was endowed with. But to continue the cricketing analogy he is essentially a dour defender rather than a successful attacking player.

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

John.Warhurst@anu.edu.au