The Treasurer Josh Frydenberg described David as "a person of the utmost decency, always professional, highly capable and deeply committed to serving his country".

The leader of the opposition, Anthony Albanese, described David as "a giant of the public service".

The former prime minister, Kevin Rudd, said that "over the course of his career, David was instrumental in decisions that have kept our nation secure, prosperous and free. He was a kind, generous, reflective, insightful man, a rock solid friend in good times and bad. And a passionately professional diplomat, a leader in our intelligence community and, above all, a proud public servant of Australia".

After setting out to explore the professional person behind those words, and speaking to many friends and colleagues in each of the organisations in which David worked, to sister organisations overseas and to former prime ministers, ministers and members of Parliament, the conclusion is: the David each of us knew is the David all of us knew.

The David who arrived in Canberra with Robin in January 1970 is very much the same David we are celebrating today.

It is almost as if David was destined to be a senior diplomat - High Commissioner to Papua New Guinea and Ambassador to China - to be the only person to head up both ASIS and ASIO and, in supposed retirement, to chair the Foreign Investment Review Board.

David's stature, his quizzical smile, his raised eyebrows, his unique sartorial sense - the striped tie, the double-breasters, the handkerchief in the top pocket - all this conveyed a natural elegance, a certain cultured grace. Yet there was always as well the humour, the penetrating wit, the ready self-effacement.

He was a down-to-earth person: he took his job seriously, but himself less so.

In a delightful speech to the Melbourne Dining Club in mid 2010, David spoke of his journey from "junior diplomat" to "elderly spook."

"I started my diplomatic career as an innocent in Rome," he said, "where I sought to understand the wet spaghetti of Italian politics. I used to boast that I wrote the best political and economic reports ever sent to the Department of Foreign Affairs. It is a boast that nobody has ever been able to deny because, to this day, nobody has ever read them."

In the same speech, David described himself as a "linguistic geriatric" when, at the age of 34, he was sent off to learn Chinese.

As a friend there was none better.

Sue Boyd, a friend of both Robin and David since David's days at the University of Western Australia, captured it best: "David was simply a constant, loyal and thoughtful friend."

David was always generous with his friends. He was seen as the glue of the 1970 External Affairs intake. In later years, he and Robin generously hosted friends at a holiday villa in Italy, where their warm hospitality was shared with a remarkable array of people, like former heads of MI6 and other intelligence services.

Always one to see the funny side of the serious, David once confided that on one occasion when he got up to leave after a promotions interview he opened the wrong door and stepped into a closet instead of the hallway. Asked what he did then, David smiled, and said he simply commented to the committee that it was more usual to be coming out of the closet!

But his sense of humour could be mischievous, as his close friend Colin Heseltine discovered in Hong Kong when David put him into a taxi, then threw in a durian and took off. Those who know the impact of durian on the olfactory senses will understand Colin's discomfort - and David's mirth.

David worked hard, very hard, often through the night in the company of a good red wine.

But he was not single-tracked: equally at home discussing classical music; sport; the history, culture, people and politics of a diverse range of countries; and Australia's geostrategic challenges, David was a man for all seasons, always good company.

In the workplace, David was a mentor, a fine communicator, a calm leader, with balance and perspective, always ethical - and more at ease with technology than most of his generation. The one thing he could not abide was impediments to providing the best possible advice to government.

David had a great eye for talent. In 1984, when Richard Rigby was in Beijing interpreting for Prime Minister Bob Hawke, David asked Richard whether he had met "the young blonde kid", as "we will all be working for him one day" - a reference of course to future prime minister Kevin Rudd.

Subsequently, David became godfather to Nicholas Rudd. At the christening, David asked the celebrant whether all new babies looked like Winston Churchill, to which the good cleric replied that he discouraged babies from smoking cigars. Divinely inspired wit, said David, had trumped his earthly banter.

David sent Nicholas a gift every year thereafter, one of which was a set of Churchill's A History of the English Speaking Peoples.

David never just did his job. He immersed himself in it, always seeking deeper understanding. Not for him a mere descriptive account of what was going on: he needed to get behind it.

So it was that on posting as Deputy Head of Mission in Jakarta between 1988 and 1990, David wrote two books about the culture of Indonesia.

One, Leather Gods and Wooden Heroes, explained the philosophical and ethical foundations of the traditional Javanese wayang puppetry, one of Indonesia's most sophisticated art forms. His Ambassador at the time, Philip Flood, has said David's book, widely acclaimed in Indonesia, was the equivalent of translating Shakespeare into Bahasa, with commentary.

As a former chair of the Parliamentary Joint Committee on Intelligence and Security, Anthony Byrne, said: "David's world was one of great colour, texture, movement, nuance and complexity. A world analysed and explained in all its facets and from every angle and from a great mind matched with a huge heart."

David's deep immersion in that which engaged him professionally continued in his formal retirement as a director of the Cyber Security Research Centre and patron of the Australian Professional Intelligence Officers Association.

David worked equally well with both sides of politics: appointed to PNG by Labor, to China and ASIS by the Coalition, to ASIO by Labor and to the FIRB by the Coalition. For him, non-partisanship was essential to his role as a public servant.

David's professional achievements are too many to recount in full, but some demand mention:

Robin, you have been so much a part of all David was - and all that he achieved. No one would doubt the importance to David's success of his wonderful partnership you, his soulmate.

For Peta and Antonia, and for Lachlan, Kaela, J'aime and Zoe, in addition to the person you knew and loved as father and grandfather there was a man who deserved all those tributes that prime ministers and others have paid.

He served his country, and served it well. You should all be proud of him.

Rest in peace, outstanding servant of the public, friend to so many of us.