The best example of this is with single-mothers' pensions, the implementation of which in 1974 transformed the lot of young pregnant girls facing poverty, social disgrace and continuing disadvantage. The mothers suffered; so too did the children. The law, and the absence of help from the social security system, was itself a sign of moral disapproval; the practical difficulties of young single mothers were reflected in the high rates of agonised relinquishment of babies for adoption.

Cullen's living depended on his having business clients, but he always leavened such work, absorbing as it often was, by adopting causes close to his heart, and pushing them with all of the energy and enthusiasm as if he were on a very handsome retainer.

It was not a matter of a bleeding heart, though he had one. For him the essence of successful lobbying and public advocacy was calm, careful and rational understanding of one's situation, of determining where one wanted to get, and of devising the strategy and the tactics that would be necessary to get there. This was a rational process, even if the tactics and the strategy might have to involve the right mixture of appeals to the heart as well as the head.

Nor was he a lobbyist of the sort who dealt in insiderness, mutual obligations, or the peddling of influence. He believed that good lobbying consisted of making a reasonable case - a case so rational, indeed, that it would be adopted by others as their own and as the right thing to do.

In some cases the business of the lobbyist is in understanding how the government system works, including knowing which public servants, which politicians and which advisers had carriage of, or responsibility for, particular policy or programs. Even smart and clever businessmen and women are not usually expert in how power is exercised in the public sector, in the arguments that are likely to work, or the arguments which will needed to counter perfectly reasonable objections or claims of higher priorities.

At other times, the lobbyist helps shape the arguments and make the case, but may also be advising about shaping public opinion, creating a demand, or, sometimes, neutralising potential objectors and enemies. With single mothers' benefits for example, it was entirely predictable that churches and conservative thinkers would see benefits as some sort of charter for, or incentive to, sexual promiscuity, likely to make even worse the feared outbreak of permissiveness and irresponsibility by the youth of today. As a strategy to counter it, Cullen focused on the rights and needs, and practical disadvantage of the children being brought up by single mothers, argued persuasively about Christ's focus on looking after children, and, was at the end, able to turn archbishops and some other likely forces of hostility into champions of helping the children, and their mothers.

About the same time, Cullen was, professionally, the champion of Bob Ansett, the owner of Budget rent-a-car, seeking to break down a cosy airport monopoly for rental cars held by Avis, a company Ansett's estranged father, Sir Reg, was to come to own. Avis argued that there really wasn't enough business at airports to warrant several operators, but, in any event, its rights were secured by contract, and it had little incentive to lower prices. Cullen helped Bob Ansett make the issue of open competition a national issue, one that was disadvantaging customers as much as it was depriving governments of revenue from proper tenders. It was a long and drawn-out fight, with established business lobbies of the day by no means necessarily in favour of open markets and the benefits of competition but Bob Ansett's ultimate victory was to make him millions.

We would sometimes joke that Cullen adopted causes in part to appease his conscience, or his reputation among his friends, for serving capitalism so well. It was hardly true - the relentlessness with which Cullen promoted the interests of his clients was a function of his believing in them - but that there was little doubt that he relished the opportunities his work gave him to help promote some other causes that proved himself a good guy, with his heart in the right place.

He argued for increased professionalism, and higher pay, for nurses in the 1970s, and helped devise the industrial strategies and tactics that allowed the nurses - unwilling to do anything that imperilled patient care or the good opinion they enjoyed among the public - to make and win their case. Not much differently, but for reward, he argued for the rights of dental technicians to deal directly with members of the public, rather than through dentists.

He adopted the cause of Christmas Island workers, mostly Malays and Chinese Malays, working on an indenture system, at Malayan wage rates, in the phosphate mines. The workers had no residence rights; indeed, they were returned to Malaya or Singapore each year, then re-engaged, so that they could not accumulate rights by uninterrupted residence or long service. Their families had even fewer rights, and no one seemed to much care. Cullen adopted the Union of Christmas Islander Workers, and its charismatic, if somewhat crazy general secretary, Gordon Bennett, and made national and international cases about the workers, their wages and conditions. Within a few years, if sometimes by slow steps, the workers had achieved residence rights, then complete citizenship, including the right to move to Australia proper, were working on Australian wages, and even had a form of self-government. That the mine was ultimately to play out was not a consequence of this improvement in their pay or rights, even if, a time before, the peonage of the workers had helped keep the cost of superphosphate down for Australian farmers.

Peter Cullen, who was 87 at his death, was one of the very first professional university-trained political staffers, serving first with Senator Pat Kennelly, a Labor character and power, particularly in Victoria, and not least during the years of bitterness and division leading up to and following the Labor Split of 1956. There are a million stories of Kennelly as the political operator - perhaps almost as many as about Whitlam; a good many of them I learned from Cullen.

But if he was a trained professional, he was not in any sense a "suit" of the modern type, not that there was much in the way of employment for political staffers until the 1970s. Cullen knew where he came from, and was steeped in Labor thinking and tradition, even if he was one of those keen to see the party adapt to modern conditions and the modern world.

In 1964, Cullen switched to working in the office of Whitlam, the deputy Labor leader, as Whitlam's private secretary. He was with him for four tumultuous years, which embraced Labor's adoption of state aid, turmoil over Vietnam, active warfare between the leader, Arthur Calwell, and Whitlam, and, after Whitlam took over, his crash or crash-through confrontation with the "twelve witless men", and Whitlam's resignation, then re-election as leader. It was also the time when Whitlam and his team were preparing the reshape the party, long out of power, to make it fit for government again, with intensive work on party organisation reform, on conceiving, arguing and making the Program, and on Whitlam's progressive mastery of the successor of Bob Menzies in the House of Representatives.

Cullen left Whitlam to become Canberra's freelance lobbyist in 1968. He was far from the only lobbyist, but the greater proportion were as they still are, if nowadays in much greater numbers, people working on the staffs of national associations and institutions, or directly for big companies. There were also groups of public relations and advocacy people, often with some political connections, offering professional advice on dealings with government, whether directly with politicians or with sections of government, not least in customs and tariff matters. But it was novel to have a single operator with a small array of clients, usually on retainer, and both quietly watching for their interests while also, often, arguing for them over a particular problem. In many cases, of course, the problems were not primarily political, but involved securing a hearing from administrators without much idea of the client's case or circumstances.

In the early 1970s, Cullen took on a young associate, a former schoolteacher, Ros Kelly, whom he nurtured into a strong interest in politics and government, and encouraged into an ultimate political career, first in the ACT, then as member for Canberra and as a cabinet minister in the Hawke and Keating governments.

Cullen did not think he dealt in an arcane art, and spent a good deal of energy passing on secrets, such as they were, of advocacy and lobbying to community groups. He wrote several books on the subject - less successfully, he ventured into some political fiction. If no great bon vivant, he was well connected, deeply respected, and a great companion and adviser.

In July, knowing himself to be dying from cancer, he organised his own wake on a Saturday afternoon at the National Press Club. Many of his family, friends and aquaintances, and not a few of his old clients, came to salute him, and to drink a toast to him. Alas, he would not allow speeches, except from himself, and even then said all too little. There were one or two present, not least Graham Freudenberg, whose words, had they been allowed would have sung as they did for Whitlam on Wednesday. Like his old boss, Cullen was capable of making a difference to the world.