China's word-of-mouth movie sensation "Dear You" held its British premiere in central London on June 20, ahead of its theatrical release in Britain and Ireland on June 26. 

"Dear You," a low-budget film shot largely in the Chaoshan (Teochew) dialect, has become one of China's most unexpected box-office successes this year. 

The story follows a debt-ridden young man who travels from the Chaoshan region in south China, one of the major origins of the Nanyang migration, to Thailand in search of his grandfather and uncovers a family secret linked to "qiaopi," letters and remittances sent home by overseas Chinese. 

Huang Ping, executive chairwoman of the London Chinatown Chinese Association, said at the premiere that the film's themes of family affection, homesickness and companionship are familiar to many Chinese living overseas. 

"The feelings for family and homeland conveyed by the film transcend time and distance and the film also reflects the Chinese values of cherishing personal bonds," she said. 

Between the 19th and early 20th centuries, millions of Chinese left the country's southern coast for Southeast Asia in what historians now call the Nanyang migration. Many eventually settled in Singapore, Malaysia, Indonesia and other parts of the region, forming part of today's overseas Chinese communities. 

Actor Zheng Runqi, speaking to the audience via video link, said many people from the Chaoshan region, along with other overseas Chinese, have put down roots in Southeast Asia and Europe. "I hope that hearing the familiar dialect in the film brings them a sense of happiness," Zheng said. 

Liu Shiyi, a London-based entrepreneur who grew up in Chaozhou, south China's Guangdong Province, told Xinhua that his parents subsequently found old "qiaopi" preserved by the family after watching the film in China. The letters had been sent back by his great-grandfather's elder and younger brothers. 

Family archives such as "qiaopi" offer personal clues to what earlier generations experienced, Liu said, noting that unlike documentaries or other public records, these private letters make family history feel immediate and tangible. 

The sensation had grossed more than 1.8 billion yuan ($270 million) at China's domestic box office as of Friday, according to ticketing platform Maoyan.