I muttered an abusive riposte. This breaks the first rule of dealing with demonstraters even when they stick their murderous contorted faces slap-bang in yours. Expressionless and silent, always the better course. This, as I entered the Manning Clark Theatre at the ANU where 430 had come to hear me speak but ten Trots were protesting at my views on irregular migration. My realist views. As I argue in the diary, if the arrival of irregular migrants had become 3,000 a month as in early 2013, the annual intake blows out to almost 40,000. This would crowd out our 20,000-a-year humanitarian intake.

In my diary I quoted Kevin Rudd at cabinet on 11 July 2013, asking an adviser how high this number — those brought by people smugglers — might climb. Up to 50,000 a year, the adviser replied. Even higher, I thought, as smugglers in Asian ports sensed opportunity. Hence the case for Kevin Rudd’s arrangement with Papua New Guinea which in my diary I called ‘a masterstroke’. Or plain good policy. The militants or romantics in the refugee lobby won’t tell us the annual level of irregular migration that they would find acceptable. A hundred thousand? Or 150,000?

Having made the point they wanted no restraints on irregular arrivals, the protesters trooped out. No rough stuff, no swearing. I then spoke and started by telling the audience I stood for a generous refugee intake yet if people smugglers were allowed to bring a number equivalent to one quarter or one third of our annual migrant intake, then Australians would simply throw out their government. After my stump speech on the Carr diaries I signed copies, many for young officers of DFAT and Treasury.

‘Those steel-cut oats — how do you get them?’ A merchant banker asked me this as, side-by-side, we checked out of the Realm Hotel. My diary (a diet and exercise book with a filigree of diplomacy in its pages) has made them a force in our national life, with health food stores selling out. But I never remember why they are more energising and life-sustaining than rolled oats. I leave those details to my wife Helena. As the three-time Democratic candidate William Jennings Bryan was fond of saying: ‘I will look up the arguments later.’

Federal parliament is a failed Mogul mausoleum I insist, talking to Alex Sloan on ABC radio in a relaxed half-hour interview. The ceiling of the Senate chamber rises like a Romanesque cathedral, a contrast with the mainly municipal babble that takes place under its vaults. The public space between the two chambers is vast and generally empty, yet there’s no space for easy socialising like the tearooms of Westminster, just a cramped little café with tables spilling into a hallway. The only artwork any visitor looks at are portraits of prime ministers. Nothing personal, I tell my Canberra audience, but having to enter its corridors on a Saturday night had been a melancholic low point.

At the Australian Centre on China in the World, I talked to director Geremie Barmé about Douglas Berry Copland, the Australian ambassador to China from 1946 to 1948. His cables told the story of Kuomintang corruption and decline and predicted the advent of Mao. Geremie told me the young scholar William Sima is working on this precious archive: it makes for powerful reading. Copland returned to Australia with the scholar C.P. Fitzgerald in tow, set up Pacific and Asian Studies at the ANU and served as vice-chancellor of the university. Public service and scholarship: Canberra ethos at its best.

More of this flavour at Manning Clark’s home in autumnal Forrest where I will be interviewed by his son, journalist Andrew Clark, before an audience of about 60. But first I climb a ladder into the historian’s old study. The desk shows the indentation of years of writing by pen his six-volume history. I remember as a university student loving the attention to W.C. Wentworth, Henry Parkes, George Reid and Robert Menzies. ‘He believed in the career open to talent,’ was the Clark refrain for each of these nation-building politicians. Yes, career politicians: honourable calling.

Andrew Clark drives me back to Sydney. Not as many trucks on the road as there might have been; we make good time. He tells me his father knew Menzies. I guess in the village atmosphere of Fifties Canberra it was possible.

I like the story of Menzies hosting Sunday night dinners at the Lodge for his public service mandarins. An American I met had dined with Menzies after his 1966 retirement and told me he had found his conversation ‘mesmerising’. I passed this on to his daughter Heather. I had liked her story about a primary school student from across the road knocking at the door of the Lodge and asking her father for help with a school project about Australian government. Along with the isolation of the old bush capital, there must have been a leisure and intimacy. Not so bad a place, I think as our car cuts through the darkness.