"Bird", featuring Barry Keoghan as a young dad, is an early frontrunner at the Cannes Film Festival with its tough but sweetly fantastical tale of working-class England.

Irish actor Keoghan is one of Hollywood's most sought-after stars following hit film "Saltburn" and his Oscar nomination for "The Banshees of Inisherin".

But it's 14-year-old newcomer Nykiya Adams who carries the movie, dealing with a world of gang violence, poverty, teen pregnancy and abusive parents -- and who finds support from an otherworldly character called Bird (played by German actor Franz Rogowski).

Keoghan said there were "a lot of similarities" to his tough upbringing in the Summerhill neighbourhood of Dublin and he could easily relate to his character, Bug: "A pure chancer, a pure charmer."

"I've been saying in interviews since 2015 that I wanted to work with Andrea Arnold and then the opportunity came. I wasn't even given a script... I'd do anything she makes," said Keoghan, who will soon star as the Joker in "The Batman Part II".

"Bird" director Arnold is one of Britain's most acclaimed directors, with an Oscar for short film "Wasp" and three Jury Prizes at Cannes for "Red Road", "Fish Tank" and "American Honey".

She said she wanted to capture the rich life of Gravesend, a working-class town an hour from London, close to where she grew up.

"There's a load of life, probably because it is so working-class. I grew up in a working-class family and they were not afraid to express themselves," she told AFP, laughing.

She said they found their young star by asking schools in the area for "their naughtiest kids".

"Interestingly Nykiya wasn't quite the kid I had in mind, but she really struck me as having this presence," Arnold said. 

 'Always been a dancer' 

 As always with Arnold's films, there is an ultra-cool soundtrack featuring bands such as Fontaines DC, Sleaford Mods and Burial.

"I've always been a dancer," Arnold revealed.

"At age 13 I was out four or five nights at clubs. I'd get in for free because I always started dancing. I'd go wearing flat shoes and really comfortable clothes. I was straight on the dance floor and I was there all night."

In typically understated fashion, she first met Keoghan in a cafe and they immediately hit it off.

"I just loved him. I love the way he looks and he feels very real to my world. It was Halloween and I think he was very amused because I gave him a toffee apple and some pumpkin," Arnold said.

The Hollywood Reporter called "Bird" a "warmhearted fable", while Deadline said it's "a jolt of culture shock that makes way for universal human truths".

It is one of 22 entries for the Palme d'Or at the Cannes Film Festival, which concludes with its awards ceremony on May 25.