London: When Japan invaded Hong Kong in 1941 during World War II, more than 60 British servicemen and a one-legged Chinese admiral, Chan Chak, managed to slip out of the island to freedom.

Now, 70 years on, descendants of the sailors, special operations agents and intelligence officers involved in the escape have pieced together their fathers' diaries and letters to create a compelling account of what happened.

The story of their escape has been stitched together in a new book, 'Escape from Hong Kong', by Tim Luard, a former BBC correspondent whose father-in-law was a special operations agent and a part of the escape team.

"The decision to prepare some means of escape for the Admiral was taken 'at the highest level'," a daily quoted Luard as saying in his book.

In fact, the plan to flee Hong Kong was hatched in the run-up to Christmas 1941, as tens of thousands of Japanese soldiers overwhelmed the colony's meagre defences and were poised to take the island, says the book.

And, as the enemy approached, the British government realised the importance of getting Chan Chak, a redoubtable, if diminutive, wooden-legged Chinese admiral to safety as he was the most senior Chinese official on the island.

"The escape was so dangerous they thought they would not survive. I remember when we made it to the mainland ourselves and met up with him how exciting it was. My father was a really tough guy," remembered Donald Chan, the admiral's son.

After boarding the boats, the escape party slipped across the straits at night, landed at Nanao, and then began a march across the Chinese countryside with the admiral put in command -- the first time a Chinese in-charge of a British force.

"My father never really talked about it. The story only came out when we saw the scars on his back when we went swimming, but it was my mother who told us," said Sheena Recaldin, the daughter of David MacDougall, an escapee who became Hong Kong's first post-war acting governor.