Actors all over Hollywood - and more than a few in Britain, no doubt - were probably counting their retrospective blessings last week, or cursing their bad luck. In the first category are those with the good fortune to have appeared in a film by the late, great iconoclast Robert Altman, many of them A-listers who’d gladly taken a pay cut for the privilege, and in the latter those who never had the chance and now never will.

Virginia Madsen offered a little insight into Altman’s brand of directorial magic in the summer of 2005, during an interview on the set of A Prairie Home Companion. The film, still to be released in the UK, was written by Garrison Keillor, Middle America’s modern-day Mark Twain, and shot entirely on location in his home turf of Saint Paul, Minnesota. Surrounded by a cast that included Meryl Streep, Woody Harrelson, Lily Tomlin, Lindsay Lohan, John C Reilly, Tommy Lee Jones, Kevin Kline and Keillor himself, Madsen was practically glowing with pleasure. ‘This is what it should be like to make a movie,’ she said between camera set-ups. ‘I knew from the first day. Something about it was like, “Oh, it’s gonna be all about creativity”. And because Bob is so generous, we all want to go the extra mile for him.’

Altman first hit the big-time in 1970 with the Korean-set (but Vietnam-conscious) war comedy M*A*S*H. Then in his mid-40s, he was already too long in the tooth to earn a place on the list of movie brats, headed by Lucas and Spielberg, whose nose for massive popular success would so impact the industry later that decade. Artistically Altman was neither naïve nor calculated enough to qualify as mainstream, nor could his work ever be deemed profit-motivated. However playful his movies might be, they were also grown-up, with an unforced, organic style that marked Altman out as a quintessentially Yankee counterpart of European directors.

The string of films he made between M*A*S*H and his crowning achievement, the country-and-western kaleidoscope Nashville, in 1975 - including McCabe and Mrs Miller (a lovely, elliptical dark dream of a Western), The Long Goodbye (a hip update of Raymond Chandler’s Philip Marlowe and the whole private eye genre) and Thieves Like Us (a pearly, lyrical alternative to Bonnie and Clyde) - are indelibly part of a golden age of pre-Sundance independent American cinema. It was then that Altman first offered up his unconventional and collagist approach to character-driven storytelling, with large ensemble casts often observed by a roving camera and heard via overlapping, multi-track dialogue. As a cinema-loving friend of mine put it, ‘All those half-heard conversations . . . He turned us into eavesdroppers, onto a world we thought we knew.’

After what appeared to be a career slump in the 1980s, the distinctive techniques Altman developed were employed to masterful effect in the ‘comeback’ films The Player (savvy Hollywood satire), Short Cuts (a tragi-comic epic à la Raymond Carver) and, latterly, Gosford Park (a period murder mystery set in England). He was an anti-institutionalist re-inventor of genres whose films are populated by a stream of misfits and eccentrics, loners, lovers, losers and dreamers.

Naming Altman’s best is easy, but there are lesser-known or unjustly neglected films worth tracking down. (Consider Vincent and Theo, with Tim Roth an utterly compelling Van Gogh.) Some flopped big. (Check out the underrated live cartoon Popeye, shot on a purpose-built outdoor Maltese set that can still be visited and featuring songs by Harry Nilsson). Others badly misfired. (Who remembers the anarchic teen comedy OC and Stiggs?) All of them are worth watching despite any shortcomings or pretensions. Some day I can see myself returning to the fascinating enigma that is 3 Women, the fragmented madness depicted in Images, the off-the-wall Brewster McCloud, the twisty nuptials of A Wedding, and the feverish Nixon portrait, Secret Honor, to name just a handful of titles. At some point I’d coast again through the often flat-footed fashion industry farce Ready to Wear, aka Pret a Porter, or the odd, off-kilter ballet world opus, The Company. Why? Because, even when not on top form, Altman can adopt an unexpected and revelatory angle on people and living.

The 80-year-old director that I met during the Prairie Home Companion shoot seemed both shrewd and utterly direct, gruff and yet easygoing. ‘I have no vision for this film,’ Altman admitted. ‘It’s moment-to-moment filmmaking.’ Only someone completely secure within his craft could get away with that. Of course he knew what he was doing. And by doing it so well, he provided us with a wealth of moments to cherish and revisit.