We all think we know who Paddington is. He comes from darkest Peru, he loves marmalade sandwiches, was named after a train station and found a home with the Brown family. What you might not know is that he's really a woman called Lauren.

Of course that is not how we see him on the big screen, rendered to furry and cuddly perfection and voiced by Ben Whishaw, but it turns out that is how it was on set during the filming of the highly anticipated Paddington 2.

Instead of actors having to imagine the famous bear, who will then be added to the film later through computer wizardry, Lauren dons a blue duffel coat and red hat with bear paws on her feet to help actors get into not only the right spirit, but also the right eyeline.

"All acting is pretending anyway," says Hugh Bonneville, who is reprising his role as Mr Brown. "And you're just projecting a lot of that pretence onto something that may or may not be there. We have a lot of help in different ways."

Madeleine Harris, who is back as Judy Brown, adds: "We have Lauren who stands in as the bear and she's so lovely. She's really great, and if we're doing a scene where we were are all moving it's so helpful to have her there obviously, because then we have an eyeline all the way through instead of someone holding a stick in shot and trying to move it in the same way the bear would.

"And then we have Gus, who is absolutely brilliant at voices and he does a really good impression of Ben Whishaw's voice, so it's brilliant, you can almost imagine the reactions to give and it makes it so much easier because instead of talking to nothing you do have something to react to and you can actually act."

And these stand-ins include the crucial duffel coat and hat? "Yes!" Samuel Joslin, who reprises the role Jonathan Brown, affirms. "And she (Lauren) has little woollen bear feet. I remember in the first one there was a bit that was cut out where there was a dog barking at the bear and she had to wear these little glasses that had a sausage on it to get it to look at her."

The first Paddington film, released in 2014, was a smash-hit and so it was almost inevitable the bear and the Browns would be back for a second adventure.

While the first outing saw Paddington pitted against Nicole Kidman's psychotic taxidermist, who wanted to see him stuffed in a museum, the second sees him take on Hugh Grant's vain and embittered actor, whose best days are well behind him, after he is framed for a crime he did not commit.

Grant, who dives into the role with gleeful abandon, is a new addition to the cast for the second go-round, and, running his hand through his trademark floppy hair, jokes he had very mixed feelings about the part of a pompous thespian who has resorted to doing dog food adverts.

"It was hurtful," he says, with a wicked glint in his eye. "But it came with a lot of money attached. It was a very funny script and I hadn't seen Paddintgon 1, so I then watched it and laughed and cried and all those things, then I went to meet Paul (King, the director and co-writer). I found him a little weird to be honest but it was a very easy thing to say yes to."

His character of Phoenix Buchanan was even originally called Hugh Grant in early versions of the script, according to King and fellow scribe Simon Farnaby. "It played into all those psychoses of every actor, I think," Grant muses, "Deep, dark impenetrable narcissism and insecurity and selfishness and greed." Bonneville chimes in: "As Mrs Bird says, we are some of the most evil people on the planet - we lie for a living."

But for the Downton Abbey star, who looks a million miles away from Lord Grantham in a pale pink shirt, casually unbuttoned at the neck, the chance to lie for a living in films about a fixture of his childhood is still a happy novelty. "My folks read me the stories when I was a kid and then they became the first books that I read for myself, so I've had a long history with Paddington and he's been my pal for a long time so it's nice to meet him in this incarnation too."

And Bonneville isn't Paddington's only famous pal. Pictures of the Duchess of Cambridge dancing with the bear shortly after she announced her third pregnancy were enjoyed around the world.

"Paddington is a national treasure," Bonneville adds. "And it's lovely to be associated with it. Bearing in mind the first book was published in 1958 and its themes of a stranger in a strange place looking for the hand of friendship and acceptance and trying to fit in, I think that is one of the reasons this character has resonated down the decades, because we have all been that person, we have all been in that situation.

"We have all been a Paddington in a new school or a new country, in a new town, and I think that is not just a British characteristic, it's universal, and that is one of the reasons he's survived, as well as the fantastic scrapes he gets into. I'm enormously proud to be latterly associated with the books I grew up with."

Those books were, of course, penned by Michael Bond, who first created Paddington after spotting a forlorn bear on a department store shelf on Christmas Eve. The author made a much-lauded cameo in the first movie, cheerily raising a glass to the bear as he arrives in London. In a sad turn of events, he died on June 27 this year, the final day of shooting on Paddington 2.

"There is an extra element of poignancy to that," Bonneville says. "Karen, his daughter, has taken on the mantle of protection of the bear and she says the second film looks after him just as much as the first one did, so we feel she's part of the family and we are part of her family, and it's all thanks to this beloved bear."

  • Paddington 2 is released in UK cinemas on November 10.