Belsize Park author Lesley Downer has made her name writing novels about Japan, the most recent of which is The Shogun’s Queen

On one of my first days in Japan, I was asleep on the seventh floor of the Nagaragawa Hotel in Gifu when my bed started rocking alarmingly. It was my first earthquake, though I soon became blasé about such minor tremors.

I was there to teach English at a women’s university. I stood out so much in this nondescript city of half a million people that when someone I’d met turned up at Gifu Station and asked for “the foreign woman teaching English”, they sent him straight to my university.

It was lonely at first but as I absorbed myself in Japanese culture I began to fall in love with the place. I bore in mind the tale of the Choshu Five. They’d smuggled themselves to London when leaving Japan was punishable by death and must have suffered far greater culture shock than I ever did.

In their day Japan was made up of 260 princedoms under the overlordship of the shogun (military ruler). In 1853, the American Commodore Matthew Perry arrived with four steam ships to force Japan to open to trade, quickly followed by England, France, Holland and Russia. The Choshu students were well aware of the power of western military might and wanted to acquire such scientific knowledge for themselves.

In Yokohama they cut off their samurai topknots, put on western clothes and on June 27 1863 smuggled themselves onto a British steamship. They had to hide in the coal bunker till the ship was well out to sea.

But in Shanghai things went wrong. Hirobumi Ito and Kaoru Inoue were mistakenly put on board the SS Pegasus as crew. They were forced to scrub decks, wash dishes and spread sails with nothing but ship’s biscuits, tea and rainwater to live on. They had terrible quarters and were horribly seasick, but they didn’t speak enough English to explain that they’d paid to travel as passengers. The other three went in comfort on another ship.

After 135 days at sea the five were reunited in London, Ito and Inoue “looking like hungry crows”, according to Inoue’s account.

After that, things looked up. They were introduced to Alexander Williamson, Professor of Chemistry and Practical Chemistry at University College London. They lived with his family and his wife, Catherine, taught them English, though they still found the food difficult to stomach.

They’d been there less than six months when Ito read in the Times that England, France and Holland were planning an attack on Choshu to force the daimyo (their domain lord) to allow western ships to pass through his territorial waters, the Straits of Shimonoseki. Ito and Inoue rushed back to warn Choshu not to fight. They’d seen enough of western technology to know that they would lose.

The other three stayed on. They studied chemistry, engineering, maths and physics and visited the Houses of Parliament, the Mint, the British Museum, military facilities and factories. They were particularly interested in the underground railway, which opened the year they arrived.

All five became pioneers of modern Japan. Ito was prime minister four times and wrote the first constitution, Inoue was the first Foreign Minister and the others developed Japan’s technology, railways and mint.

Back home in London, I immediately tracked down the house where the five had lived. I was thrilled to discover it was just around the corner - 16 Provost Road, behind Chalk Farm station. There is a monument to them at UCL, with their names engraved on the polished black granite and a haiku: “When distant minds come together, cherries blossom.”

I was intrigued by this watershed period when Japan changed virtually overnight from a feudal society where people walked or went by palanquin to a western-style country with telegraphs, trains, gas lighting and lighthouses - largely under the guidance of the five young men who had lived in London.

Then I began to come across references to the Women’s Palace. In all my time in Japan I’d never known that the shoguns had had a harem of three thousand women, so secret that no westerner even knew it existed. When the shogunate fell the palace was closed down and the women fled. They’d been on the losing side and many of their families had been killed. I wondered what had become of them but there was no evidence at all so I set my imagination to work. The Shogun’s Queen is the first of my quartet of novels set in these turbulent years and takes place largely in the vast harem in Edo Castle.

The Belsize Park local is author of many books on Japan, including Geisha: The Secret History of a Vanishing World, Madame Sadayakko: The Geisha who Seduced the West and The Last Concubine. Her new novel, The Shogun’s Queen is published on November 3.