When I was about your age, older people were good enough to take me under their wing. One of them was John Howard – Australia’s second longest serving prime minister, in whose government I later served. Another was BA Santamaria, whose movement had helped to keep my side of politics in office for 23 years, and whose allies helped me to win the student presidency at Sydney University.

And there were some wonderful teachers, including Brian McGuiness, Geoffrey Marshall and Neville Maxwell, who tutored me here in Oxford. I hope I can repay, some of the debt I owe to them by sharing briefly with you what this place did for me, and why I think it matters.

There’s a line of Evelyn Waugh, a Hertford man, of time at Oxford, “it was this cloistral hush that gave our laughter its resonance and carries it still, joyously, over the intervening clamour”.

I still recall the day I arrived in England – the plane flew low up the Thames Valley and I gazed in wonder on the Houses of Parliament, Big Ben, St Paul’s, Tower Bridge – the great landmarks of the country that had shaped my imagination; as it does the mental hemisphere of everyone who speaks English, which these days is the world’s common language.

Oxford has educated 27 British prime ministers. It’s also educated four Australian ones: Malcolm Fraser, Bob Hawke, and Malcolm Turnbull, as well as your speaker tonight – and, of course, one US president, who smoked but supposedly didn’t inhale, presumably because he couldn’t read the no smoking signs at Rhodes House which were in Latin.

I could hardly contain my excitement, arriving at this university that for centuries had attracted the world’s best minds. Mind you, delusions of grandeur lasted only until my first dressing down by the college porter, and delusions of adequacy didn’t survive my first tutorial, an essay that was a collage of quotations – on Descartes’ theory of knowing – which led my don, I’m sure, to suspect that he was stuck with just another muscle-bound rugby player from the dominions.

Eventually I worked out that what was expected of me was not a regurgitation of someone else’s ideas – but my own, based on a thorough assimilation of the best that’s been thought and said. The Oxbridge tutorial system, of careful study followed by an attempt to work out for yourself what it all means, is the perfect preparation for journalism and for politics – both of which I gravitated to.

It also reinforced my instinctive conservatism. It’s hard to regard yourself as morally superior to your forbears when it’s their work you’re learning from. On the fundamentals of the human condition, there really is nothing new under the sun.

I can’t say that all the Abbott government’s policies were shaped in Oxford, but their author certainly was. October 1981, when I arrived, was the middle of Margaret Thatcher’s campaign for cruise missiles to be based at Greenham Common. For a fortnight or so, contemplating the potential annihilation of so much history, I became a nuclear disarmer – and then I remembered that great ideals could never be destroyed, and should never be surrendered.

When – at my final Provost’s collection – the late Lord Blake observed that “Mr Abbott needs to temper his robust common sense with a certain philosophic doubt”, it was perhaps a coded message to enter the world of action, rather than reflection. But I’m confident that striving “to say what you mean and to do what you say” – which is how I tried to conduct my public life – owed much to tutors here who insisted that people who couldn’t explain things, didn’t understand them; and that the point was less analysis for its own sake, than coming to conclusions about what might be change for the better.

Have you noticed how people in authority tend to talk endlessly, without actually saying anything? In my time, you couldn’t bluff your way through an Oxford tutorial. And have you noticed how so much public debate is about demanding that things be better, without saying how this might be brought about? Again, willing the ends but not the means would not normally have made it past an Oxford tutor. And what about the current craze for rewriting history and for debunking heroes? My tutors would have seen judging yesterday’s men by today’s standards as the epitome of condescension. There were no safe spaces then – except those that could be defended by rigorous argument.

My time here wasn’t all plain sailing. I had to dictate some of my final papers to a typist because the examiners couldn’t decipher my hand-writing. To which one of my more upper crust English friends quipped: “And do you mean to say that the typist could decipher your speech”.

And yes, there was the first I never got; and the rugby blue that I missed, two years running. And I lost my only election here, for the presidency of the Queen’s College middle common room. Oxford helped to teach me how to lose, as well as how to think – and I guess two blues in boxing means that it taught me how to fight too. Oh yes, to whom much is given, much is expected.

When I was leader of the opposition in Australia, I never thought that I could remake the world or change human nature but I knew there were some basic things that government just had to do if a country was to succeed.

Government has to keep the nation’s borders under control. If it doesn’t, it risks a form of peaceful invasion. We never had illegal immigrant boats on quite the scale of those still coming across the Mediterranean – but when the people smugglers scuttled their boats, my government gave them new ones they couldn’t sink, and sent their customers back to Indonesia. It’s an example I would commend to you because the only way to save lives is to stop boats.

Government can’t tax a country into prosperity. That’s why my government scrapped the carbon tax – which was socialism masquerading as environmentalism; and scrapped the mining tax – which would have killed the industry on which our prosperity is based.

Government has to keep its spending under control. Every dollar government spends comes from taxpayers either in tax today or tax tomorrow to repay what government borrows. That’s why my government brought down the toughest budget in two decades (at great political cost).

Government exists to do what individuals can’t, whether acting alone, or in Burke’s little platoons. Only government can orchestrate major infrastructure, which my government began building on a massive scale including the Western Sydney airport that had been announced but not proceeded with for 50 years.

In just over a year, my government finalised trade deals with China, Japan and Korea which were better than they’d done with any other country. You can have strong borders and free trade – I proved that as Prime Minister of Australia.

And the easiest trade deal of all to do, would be with a country with a shared history, a common culture, a preference for freedom, and a comparable living standard. Such a country, indeed, would hardly be foreign at all, other than in a strict juridical sense; more like family.

It would be a treaty you could write on a single page, specifying zero tariffs and quotas; full mutual recognition of standards and credentials; full freedom of investment; and free movement of people for well-paid work, not welfare, with – perhaps – a modest foreign workers tax on employers to ensure that wages aren’t being undercut. And why not let each other’s young people freely spend a couple of years living and working in either country, if that’s their choice, because it would reinforce the millions of human bonds that bind us together.

That’s the deal that Australia should do with the United Kingdom, at the moment of Brexit, when Britain can once more resume a global role and destiny in the wider world.

I should confess to being one of the overseas leaders recruited to advise the British people to stay in the European Union. Britain should stay, I said, not because Britain needed Europe; but because Europe needed Britain to save it from bureaucratic paralysis. Now that the decision to leave has been made, it should happen as quickly and cleanly as possible.

As the world’s fifth largest economy, as the west’s second strongest military power, and as the home of more Nobel Prize winners than any country other than America, if there is anywhere in Europe that’s more-than-capable of standing on its own two sturdy feet, it’s this country. Hence it’s way past time for the British people to stop remoaning and to take charge of their own future.

What have the British ever done for us? To adapt the forum scene from The Life of Brian, it’s not much, except for the English language, the rule of law, parliamentary democracy, the industrial revolution – and saving Europe from the menace of Nazism. For me, it’s the EU establishment’s palpable desire to punish Britain for leaving that entirely vindicates the Brexit project.

The story of English-speaking civilisation is of “freedom broadening slowly down from precedent to precedent”, that mostly happy marriage of liberalism and conservatism that has produced societies that are far-from-perfect but are still the free-est, the fairest and the most prosperous of any on earth. It’s the greatest story ever told. And please don’t forget that it’s your legacy, too, to protect and extend. What will you do, to keep this a beacon of freedom and hope to the wider world?