China's President Xi Jinping has written a letter to a British woman whose father was rescued by Chinese fishermen from a Japanese attack in World War II.

Denise Wynne wrote to the president recently to thank the locals for their bravery, expecting to never hear back, but she said she was "honored" to receive the reply. 

Eighty years ago, Denise Wynne's father Dennis was one of more than 1,800 British prisoners of war being taken from Hong Kong to labor camps in Japan.

They were packed into the hold of the cargo ship Lisbon Maru off the coast of China when a U.S. submarine spotted the Japanese-flagged ship and fired a torpedo which struck and sunk it. 

Despite the danger, a group of local Chinese fishermen came to the rescue – and helped save Dennis and his fellow prisoners.

"He said that if the Chinese fishermen hadn't come, there would've been more carnage, there would've been more prisoners of war shot and killed. He owed his life to the Chinese fishermen," Denise said of her father. 

"He said he wouldn't have been alive and survived the years that he did and he wouldn't have had me, he wouldn't have had my grandchildren and great-grandchildren."

More than 800 prisoners of war died in the incident off the Zhoushan Islands, around 120 kilometers from Shanghai's coast.

The fishermen's bravery saved almost 400 others.

Denise wrote to China's President Xi Jinping this month to thank the locals for their heroism. Little did she know she'd get a personal reply from the Chinese leader.

"I thought it would be just put to one side and never read," she admitted, "but I'm just so appreciative that he did take the time to read it and to reply. This is such an honor."

Fifty years after establishing diplomatic ties, UK-China relations are near an all-time low.

The country's top diplomat in Britain hand-delivered the letter, hoping it helps promote understanding.

"This story which took place in 1942 is very touching. It's a testimony to this friendship and mutual support between the people of China and the people of the UK," said Zheng Zeguang, Chinese ambassador to the UK. 

Denise hopes to visit Zhoushan one day, to see a memorial being erected to commemorate the fishermen.