His posture, ramrod straight. His manners, impeccable. His breeding and entitlement obvious even if you don’t know his real name is Prince Albert Frederick Arthur George.

But the client who has been signed up for speech therapy by his gently insistent wife is only Mr. Johnson to the down-on-his-heels actor-counselor and therapist. And Mr. Johnson’s problem is as obvious as his awkwardness in simple conversation.

“I buh-bloody well stutter!”

And as “Bertie,” begins his therapy, there’s a need for him to get over this. Bertie is The Duke of York, younger brother to the Prince of Wales, and he has speaking engagements. But when his shallow, playboy brother abdicates, Bertie’s speaking calendar will only fill up as he becomes king. When Britain is plunged into World War II, a speech by the king to rally the nation is a big deal. Every ear in the empire will hang on every word of “The King’s Speech.”

One of the best films of 2010 captures the funny, touching and inspiring relationship between the man who will become King George VI (Colin Firth) and the brash Aussie (Geoffrey Rush) who tries to figure out why he stutters, and to help him over it so that the free world won’t despair every time the stammering, stuttering George opens his mouth.

Firth is the very picture of royal aloofness as Bertie, dragged to a dingy basement flat by Elizabeth, the future Queen Mother (Helena Bonham Carter, terrific) where his new teacher insists that “in here, it’s better that we’re equals.” Rush’s Lionel Logue is a delight, pricking royal decorum, prying into Bertie’s personal life and tricking, cajoling, coaching and coaxing smooth if not exactly fluid sentences from a man who suffers from a fear of public speaking that much of the world shares.

Michael Gambon is the bluff, formidable George V, the imposing father who worries that his dashing eldest son (Guy Pearce, superciliously brilliant) will toss aside the monarchy, or worse, destroy it, with his madcap affair with “that woman,” the infamous Wallis Simpson (Eve Best, a dead ringer for the divorcee).

But the heart and soul of this educational and deliciously entertaining period piece is the student-teacher relationship of Bertie and Lionel, a man who learned his trade dealing with shell-shocked soldiers returning from World War I. Lionel tries to figure out when Bertie doesn’t stammer. Try singing it.

“No. certainly not.”

Can he tell a joke?

“Ti-uhhhh-ming isn’t…my…strong…suit.”

Firth perfectly summons up a lifetime of impatience for this impediment to his speaking voice, impatience and fear. And Rush is playfully impertinent and downright rude, even as he betrays a deep sympathy for the patient’s plight.

Director Tom Hooper did the “John Adams” TV miniseries, but also the brash historical soccer feud dramedy “The Damned United.” He has great fun with this material and cast the heck of the film. Timothy Spall is a droll, stentorian Churchill. Jennifer Ehle, Firth’s famed “Pride and Prejudice” co-star is cast as Lionel’s put-upon wife. Claire Bloom plays the king’s mother, Queen Mary; Derek Jacobi an irritable Archbishop of Canterbury; Anthony Andrews the prime minister who wouldn’t put up with Edward VIII’s dalliance with a commoner.

And Hooper gives Bonham Carter every opportunity to show us why the woman generations knew as “The Queen Mum” became beloved and felt an undying enmity for “that woman,” Mrs. Simpson.

But you don’t have to know much of this history or care much for the inbred gene pool that is the British Royal Family to delight in this engrossing and moving story of an alternately warm and combative relationship, a tale told in this absurdly R-rated (one scene of comical, over-the-top profanity) screen biography.

Film focus

WHAT: “The King’s Speech”

RATED: R for some language

RATING: 4 stars

RUNNING TIME: 1 hour, 58 minutes

Colin Firth, who portrays King George VI in “The King’s Speech,” won this year’s Golden Globe for lead actor in a drama.