Renee Zellweger said her character Bridget Jones "feels like an old friend" as she and the cast of "Bridget Jones: Mad About the Boy" attended the film's world premiere in London on Wednesday.

Over two decades after "Bridget Jones's Diary" came out, the fourth movie in the series finds Bridget now a single mother of two after the death of her husband Mark Darcy.

Bridget's friend and former lover Daniel Cleaver, played by Hugh Grant, also makes an appearance in the romantic comedy.

As Bridget juggles a career, parenting, seeing friends and starting to date again, Zellweger says it is the character's vulnerability that connects with audiences.

"I think a lot of people relate to the challenges that she finds her way through, her vulnerability," Zellweger said on the red carpet.

She praised writer Helen Fielding for creating a character that many people find endearing, as well as "moments that seem universally and cross-generationally relatable."

Bridget Jones and her romantic adventures first made their mark on pop culture in Fielding's London-set 1996 hit novel "Bridget Jones's Diary".

The character's entries listing her weight, her alcohol and cigarette consumption, and details of her love life, struck a chord with audiences. Three more books followed, and a series of movie adaptations - "Bridget Jones's Diary" (2001), "Bridget Jones: The Edge of Reason" (2004), and "Bridget Jones's Baby" (2016).

In the latest big screen adaptation, the now 51-year-old Bridget decides to try dating again and ends up meeting 29-year-old Roxster, played by Leo Woodall.

"I felt a lot of pressure going into it. But then I met her (Zellweger) and she is just joyous and generous and kind and ... a wonderful actor. I knew ... it was going to be relatively easy-going forward," Woodall said.

The movie also features Chiwetel Ejiofor, who plays one of Bridget's children's teachers. Known for films including "12 Years a Slave" and "Children of Men", Ejiofor said joining the franchise was the "easiest yes."

"Renee has done an amazing job of creating this character. There are very few things that have lasted for 25, 30 years," he said.

Film director Michael Morris did not rule out further movie adventures for Bridget, but said that was ultimately up to Fielding.

"Bridget Jones: Mad About the Boy", released by Universal Pictures, begins its global cinematic rollout on Feb. 12.