MIKE LEIGH, the British writer-director of "High Hopes," "Life Is Sweet," "Naked" and "Secrets and Lies," has always marched to his own serendipitous drum, gawd bless 'im.

Within the realm of things English, he selects whatever subject he desires. And despite his growing recognition -- four prizes in Cannes and five Oscar nominations -- the charming curmudgeon Leigh refuses to alter his method for the money men.

The proof is "Topsy-Turvy," a 160-minute work of sustained brilliance and delicacy that wows you with its painstaking, effortless accumulation of detail. It is one of the few movies in recent memory that I've desperately wanted to watch again -- just so I can enjoy the nuances I missed the first time. I won't just be watching it again for the artistry. I need to catch all the jokes; Leigh is one of the funniest writers on screen today.

"Topsy-Turvy" is about the great 19th-century team of librettist William Schwenck Gilbert (Jim Broadbent) and musical composer Arthur Sullivan (Allan Corduner), at a crucial time in their illustrious partnership.

The toast of London for a decade for such delightful comic operas as "The Pirates of Penzance" and "H.M.S. Pinafore," they have run into a creative wall. After the opening night of their 1884 work, "Princess Ida," an influential London Times critic pronounces their work formulaic. And he snidely refers to Gilbert's predictably "topsy-turvy" stories, dubbing him "the legitimate monarch of topsy-turvydom."

Unfortunately for Gilbert, the ailing Sullivan tacitly agrees. It is time, declares the composer, to leave comic operas for more serious music. There's worse: London's sweltering heat is keeping the audiences away. And there's backstage dissension among the cast members of the Savoy Theatre. Could this be the end?

The ever-glum Gilbert descends into even gloomier depths of misery. And when he arranges a meeting with his partner to talk about the future -- and Sullivan's lack of enthusiasm for his latest piece of work -- the conversation breaks out from the staid confines of Victorian decorum.

Sullivan says he has always understated his music to support Gilbert's words. To which Gilbert declares he has always subordinated his words to Sullivan's music. Sullivan then points out that Gilbert's latest idea -- in which the story would turn on a magical potion -- mirrors his previous works, which use magical coins, lozenges and whatnot for the same effect.

"In this instance, it's a magic potion," insists the writer.

Sullivan will not change his mind. Later, things get worse for Gilbert when he visits the dentist.

"I must say," says the dentist (David Neville), as he brutally extracts a rotten tooth from the librettist, "my wife and I did find `Princess Ida' rather too long."

A shaft of hope pokes through the doom and gloom when Gilbert agrees to visit a Japanese exhibition in London. He becomes entranced with the Japanese culture after witnessing an exhilarating kendo sword fight, a kabuki play and a teahouse ceremony, led by a Japanese woman who can only say "Sixpence, please."

You can just anticipate what is coming. Gilbert hits upon the idea for a newer, better work, which turns out to be "The Mikado."

Sullivan loves the idea.

There are so many wonderful scenes, it would take several reviews to recount them. Writer-director Leigh, who creates his movies in close collaboration with his performers, gives us almost three hours of Victorian-era entertainment -- where humor, pain, misery and discomfort all come together in marvelous harmony.

We get to know an enormous but charming ensemble, including Gilbert's sweet-natured wife Kitty (Lesley Manville), Gilbert and Sullivan's manager-impresario, Richard D'Oyly Carte (Ron Cook), Gilbert's ear-trumpet-brandishing mother (Eve Pearce), and Savoy troupe actors Richard Temple (Timothy Spall) and Durward Lely (Kevin McKidd) -- both of whom need excessive kid-glove treatment. I even caught a glimpse of my favorite Leigh player, Katrin Cartlidge, as a Madame in one naughty scene.

But if there's one performer who defines this movie, it's Broadbent, whose appearance marks his fifth collaboration with Leigh. He delivers a fabulously hangdog performance, as he mutters some of the most memorable lines.

"No one respects her more than I do," says Gilbert, of his wearisome mother. "And I can't stand the woman."

And at the height of his success, after rebounding from the lows of "Ida" to the resplendent heights of "The Mikado," our man Gilbert seems altogether incapable of joy.

"There's something inherently disappointing about success," he says.

TOPSY-TURVY (R, 160 minutes) -- Contains nudity and strong language. Some French with subtitles. At the Cineplex Odeon Avalon 2.