It is 1938, and the cynical music impresario Max Detweiler is at the lakeside home of his friend Captain Georg von Trapp in Salzburg, where the conversation has turned to the disagreeable subject of the Nazis and Austria’s imminent Anschluss with Germany. “You know I have no political convictions,” shrugs Detweiler evasively. “Can I help it if other people do?” Von Trapp’s responding flash of anger is a genuinely compelling and grownup moment in this movie – the 1965 hit musical The Sound of Music: “Oh, yes, you can help it. You must help it.” Playing Von Trapp, Christopher Plummer’s face becomes fierce and hawkish with contempt for all those who do nothing and allow evil to flourish.

At 35, the Canadian-born Plummer became an international star in this film, but as the years and decades went by – and almost everyone swallowed their pride and admitted that they loved The Sound of Music – Plummer became the most famous and stubborn refusenik until almost the end of his life, calling it “awful and sentimental and gooey”.

But it wasn’t simply that The Sound of Music made him famous: it shaped many of the roles and personae of his screen career. The widower and retired naval officer Von Trapp was a man of fierce integrity, discipline, patriotism and bearing, but with a softer, romantic side. He, of course, falls in love with and marries Maria – the young novice nun employed to look after his children, played by the gamine Julie Andrews. Plummer was a handsome man with theatrical presence and a fine voice, who made his name first on the stage in classical and contemporary roles and continued to do much acclaimed theatre work in London and New York. Plummer was very different from the newer, realer-looking stars of the American new wave such as Dustin Hoffman or Jack Nicholson and was outside the method school of Marlon Brando and Robert De Niro. He also had something more reserved and controlled than his great Canadian contemporary Donald Sutherland. He was perhaps destined to become a character actor who would grow into his style. Even in relative youth, there could be something a bit scary, gruff and patriarchal about Plummer, but when the humanity and gentleness emerged it was all the more beguiling.

Plummer was to play Rudyard Kipling in John Huston’s The Man Who Would be King (1975), a creature of empire if ever there was one. He was the 60 Minutes TV host Mike Wallace in Michael Mann’s The Insider (1999), whose old-school journalistic candour and objectivity is vital in investigating the sins of big tobacco, with Plummer coolly playing off the more mercurial co-star performances of Al Pacino and Russell Crowe. He was perhaps typecast as the cantankerous literary genius Leo Tolstoy opposite Helen Mirren as his long-suffering wife Sofya in The Last Station (2009) – although this earned him the first of his two Oscar nominations – and perhaps most sensationally as the bad-tempered and even sinister J Paul Getty in Ridley Scott’s All the Money in the World (2017), the ageing plutocrat who appears to value his own money, status and privacy more than the safety of his kidnap-victim grandchild. Famously, he was a last-minute replacement, when Scott decided he could not endure the recently disgraced Kevin Spacey in the role – and decreed that all Spacey’s scenes would be reshot with Plummer, at enormous cost. This also triggered a range of memes on social media, showing Plummer’s face replacing Spacey’s in LA Confidential, American Beauty, House of Cards, etc. It was somehow fitting that even in the troubling and amoral role of J Paul Getty, Plummer was asserting a reputation for old-fashioned probity.

But in a way, all of these starring roles in his career, robust and valuable and intelligent as they all are, could be seen as a constellation surrounding the central star turn, the Oscar-winner he achieved late in life. It may come to be seen as his masterpiece of a performance – a marvellously unexpected masterpiece, at that. He played the elderly man, Hal, in Mike Mills’s 2011 film Beginners, who after the death of his wife comes out to his grownup son as gay, and as a result lives a far more relaxed and fulfilling existence in the remaining few years of his life than he had ever done before. But his son (played by Ewan McGregor) has to deal with complex feelings, related to the fact that Hal condemned his late wife to a world of denial and also that the mannerisms of irony and sarcasm that he has inherited from his father were originally generated by Hal’s erstwhile in-the-closet dishonesty. Writer-director Mills based the character on his own father.

The casting of Plummer is a masterstroke: the venerable Canadian actor, so often associated with conservative and hidebound roles and figures from the establishment, is just right for Hal, and there is real poignancy and fun in his portrayal of late-flowering sexual honesty and the paradox of realising what it is to be young again, although in the body of an old man: what it is to feel what young people feel and to feel some of their freedom. Hal has perhaps more freedom than the young, because he has that sense of perspective and wisdom old age has brought him. The second half of the famous phrase “If youth only knew, if age only could” now applies to Christopher Plummer’s reborn Hal.

Plummer brought a granite authenticity and presence to every role, he was the revered or feared figure from the older generation: sometimes fierce and soldierly, but more often tender, witty and humane.