The old rule that film series for children tend to go one sequel too far pretty much applies to “Paddington in Peru,” the third Paddington Bear picture to celebrate all that’s twee about a bear learning to be British

The strain of finding a proper plot for the bear to play around in is obvious before you note that five writers made it into the credits. And whenever you take a comedy built around a beloved character out of its element — be it a sitcom or a film series — that’s a give away that you’ve out of ideas.

“The Simpsons’ are going to…Knoxville!”

But a lot of the charm is still here, much of it coming from the innocent, well-mannered bear abroad, perfectly voiced by Ben Whishaw.

“You can take the bear out of the jungle, but you can’t take the jungle out of the bear” isn’t funny unless the bear has that soft, sweet voice, and the bear’s in a jacket — with a marmelade sandwich tucked under his hat.

And tossing a couple of Oscar winners into the mix — Jim Broadbent as a German-accented curio-shop owner, with Olivia Colman beaming as a too-chipper, too toothy singing nun, and vamping Antonio Banderas into half a dozen parts as generations of a Peruvian clan, pays off almost as amusingly as Hugh Grant’s villainous turn in an earlier Paddington picture.

Paddington’s back story is the subject this time, how he grew up in the Andes, lost his family and was raised by a bear who took him in — Aunt Lucy (voiced by Imelda Staunton). The bear was meant to travel all along, according to her.

“If ever you get lost, you just roar,” she counsels him. “And I’ll roar back. I’ll hear you, no matter how far away you are.”

That’s as comforting a message as any film for small children can give. And the tykes are never too young to learn what “foreshadowing” is, are they?

Because when the singing nun (The Andes are alive with the Sound of Music.) who runs the Andean Retirement Home for Elderly Bears calls, telling Paddington how much his Aunt Lucy misses him, there’s nothing for it but for the whole family to join Paddington on a junket to Peru.

Yes, the kids (Madeleine Harris, Samuel Joslin) have grown up enough to start going their own way. Mom (Emily Mortimer) is starting the empty nest weeping early. And yes, Dad (Hugh Bonneville) is still a risk-averse risk-management expert about to get laid off by his younger, risk-embracing new boss (Hayley Atwell).

But “purple kneed tarantulas” and piranhas be darned, Paddington and the Browns are going to Peru.

Aunt Lucy’s gone on a walkabout, Reverand Mother regrets to tell them. But Paddington discovers a clue to her whereabouts. If they can just charter a boat to go down river…

Banderas plays dashing Hunter Cabot, boat owner, “Svelte, strong, easy on the eye,” he purrs. “And that’s just the boat!”

He and daughter Gina (Carla Tous) will transport the Browns.

But all is not what it seems with this rakish, clumsy riverboat skipper. The walls of his cabin are decorated with paintings of his ancestors — a pushy conquistador, a crusty miner, dapper jungle explorer and aviatrix among them. And those ancestors have their own agenda, which they bark into his ears in the most insistent (and hilarious) ways.

What do they want with Paddington? When the chips are down, “Eat the bear!” may be a part of that.

There are few more reliable laughs in the movies than Antonio Banderas milking that Spanish accent to the “Puss in Boots” max.

Colman, given a song and dance number and a few subtexts to toy around with in her character, is a hoot.

Throw in some ursine pratfalls in a photo booth, a river boat and Incan ruins, with or without his family, with or without his new “brolly” (umbrella) and you’ve got a perfectly cute kids’ movie, no matter how derivative and cut-and-paste makeshift the plot might be.

Rating: PG

Cast: Olivia Colman, Hugh Bonneville, Antonio Banderas, Emily Mortimer, Jim Broadbent, Madeleine Harris, Samuel Joslin, Carla Tous, Julie Walters, and the voices of Ben Whishaw as Paddington and Imelda Staunton as Aunt Lucy.

Credits: Directed by Dougal Wilson, scripted by Mark Burton, Jon Foster and James Lamont, based on the character and books by Michael Bond. A Sony/Columbia Pictures release.

Running time: 1:46