Sir Jonathan Mills is having a signature year.

He has been knighted. And he has got hitched. All he needs to do now is preside over a successful Edinburgh International Festival, his last but one, and 2013 really will be an annus mirabilis for this fiercely intelligent, mercurial, imaginative artistic director of the world’s most famous arts festival.

Sir Jonathan, who told The Herald recently he intends to live in Edinburgh after he steps down from the festival, mainly so that he can write a new opera, is in very good form when we meet. It is a stormy day in early August. The skies are dark, and violent rain is pelting against the windows of his office at the top of the Hub on Edinburgh’s Royal Mile. When we sit down to talk, this year’s festival is about to begin. The festival office outside his office is abuzz. But first we need to talk about some personal and public celebrations. One involves the gold braided ring on his left hand, the other the light tapping of a royal sword on his Australian shoulders.

The Knighthood? It was announced in this year’s Queens Birthday Honours in June. He was in New Zealand. He was telephoned – a formal letter marked Urgent, Personal, On Her Majesty’s Service had arrived, with the look of a tax bill or jury duty request. It contained something rather more lofty, and Sir Jonathan will receive the honour on October 3.

He says: “If you buy into the hierarchy, or the hierarchical aspects of it, then you should get a life. If, on the other hand, you take it either with a dose of detachment, and bemusement, but also shared pride, then I think it is OK. I am not going to pretend whether I wondered about accepting it, but I did wonder whether this made me feel ridiculously grown up and a little old fashioned.”

Read Phil Miller's State of the Arts blog, with extended quotes from Sir Jonathan

On a shelf underneath the framed festival programmes of his tenure lies a plastic helmet, shield and sword – a wry present from the festival’s press department on the day it was announced he would become Sir Jonathan. He says: “I was pleased to accept the honour because I think any society should have a way of not only penalising people, but for acknowledging people, and it is not for me to determine the rituals of that in your society, which I am now part of. I haven’t changed my behaviour to get it. I do know people who do that, I have met them, people who line up for it which is sad, because it is just such misplaced effort – you should be authentic to yourself.”

But the timing of the award, coming in the same year as an important festival and the civil partnership ceremony with his partner Ben Divall, has made him consider time and its consequences. The 50-year-old nods and says: “I don’t feel old, I don’t feel decrepit – nor do I look it – but there is a certain rite of passage that this is part of.” Two deaths, in particular are on his mind: that of his father, Frank Harland Mills, and his friend and librettist, the influential Australian poet Dorothy Porter.

His father, who died in April 2008, eight months before Porter, has been described as one of the most outstanding surgeons Australia ever produced. In particular, his brave and tireless work, when a prisoner of war after the fall of Singapore, in the Sandaken and Kuching camps in Borneo, saved the lives and limbs of many soldiers. After the war, he became one of the world’s foremost heart surgeons. He was Sir Jonathan’s loving father, but also one of his most profound influences and inspirations. He says: “My father certainly had limits, but he happened to be a great human being – he had a very specific and rare knack: of saving people’s lives as a surgeon. He would be sent hopeless cases and he would restore them to life.”

He adds: “When you are in your 20s and 30s, you know people who die for whatever reason, but I don’t think you fully understand death and the meaning of life and mortality until one of your parents die. In my father’s case, he died five years ago, there was not a regret in the deepest sense – this was not a life cut short, he was nearly 99. Others have said he was a great man; he was also my father.”

Porter’s decline and death was, by contrast, a shock, given it was thought she had made a recovery from cancer. He speaks eloquently and movingly of how closely they worked on two operas. Her sudden decline in health was traumatic. “That was really distressing – she was 54 and that wasn’t a life that had finished its course. I had said many things to Dot, except goodbye. That was really a loss. She was a great friend.”

The Australian has become more forthcoming since he was presented to a Scottish and international press in 2006. He was quiet and a little reticent, then. But he talks eloquently, and as long as you want to listen, about the festival, its programme, art – stage one of this interview was diverted into an entertaining and informative 20-minute discussion of the music and times of Claudio Monteverdi – but he is also now willing to talk his own life, experiences and opinions.

Before being handed the reins in Edinburgh, he had been artistic director of the Melbourne International Arts Festival and the Brisbane Biennial International Music Festival. He graduated in music from the University of Sydney where he specialised in composition with Peter Sculthorpe and his work Sandakan Threnody won the Prix Italia in 2005. Over the years, he has made the EIF his own. There is a looser, more eclectic feel to its programmes. There have been hits and misses. But his plans always reveal a surprise or two, something playful as well as intellectual. There is also, of course, a theme, one of the signatures of his reign.
In 2008 it was the Fringes of Europe, in 2009, Enlightenment, and in 2010 and 2011, two memorable years looking at the New World and Asia. This year, it is technology. Next year it may be the Commonwealth (equally, it may also include Empire, and the First World War).

The 2014 festival will come at a rare point in Scotland’s history, the year of a vote on Scottish Independence. Sir Jonathan will not reveal how he will vote but seems to be leaning towards a Yes vote. “I haven’t made up mind,” he says, “although I am thinking about it seriously. The best of Alex Salmond is that he is engaging citizens like me to think about the challenges. There will be people who characterise him in particular ways, with a certain cynicism, but my experience of Mr Salmond is not cynical, nor is it opportunistic. I think he has thought deeply about Scotland’s place in the world – you might disagree with him, but there is no questioning the depth of his thoughtfulness on that subject.”

He adds: “The guy is serious, and he is ambitious. And if he does win, it will be because he is so engaged with the process, committed and convincing. There are always a thousand reasons not to do something – I am interested in why one should. How fantastic to be alive in a place where these conversations are happening.”

After he stands down from his post next year, he will stay in Edinburgh to write his new opera, based on the book Eucalyptus by Australian novelist Murray Bail, and truly live in the city, he says, for the first time. For his job, he travels frequently. “I love every minute I am here, but I am not here every minute,” he says. “It’s a very easy city to live in. It is no accident the festival functions so well here, because it is perfect for a festival, in terms of its scale. I am not putting a time limit on how long I live here.”

In March this year, he and his partner joined in a civil partnership after being together for seven years. “I got hitched,” he says with a smile. “It was in the Melbourne Room of the registry office in Edinburgh, which has connotations because we met in Melbourne.” He leans forward and adds: “Any form of public ritual just makes you reflect why you are with someone and why you value them. It has been a year of rituals.”

And how is he feeling about the prospect, I ask, of leading his penultimate EIF. “I have been in this position before, being the rooster who becomes the feather duster,” he says.

“And I quite like it because it allows me to go back and do things I want to do. There will be plenty of people who think I did a no-good job, and people who thought I did a very good job. That’s for others to judge. But the job I have done is absolutely rooted in me and my identity as a composer, so if I don’t do that, I feel I will lose that connection. I cannot wait to get back to doing those things, after this.”