Mrs Nakata gave me a peace sign and handed me one of her 100-yen (73 cents) ice creams in a cone.

With her friend, Mrs Fujitani, she runs the only ice cream stall in the Atomic Peace Park in Nagasaki.

The ice cream ladies sell out every day.

Peace is very good for business.

Both were 12 in 1945 when, at 11.02am on August 9, the US Bockscar bomber aircraft, flying from the Tinian airbase on the Mariana islands, dropped the second atomic bomb on Japan.

“It was a mistake, “ she told me.

“They wanted to bomb Kokura, but the cloud was heavy so they started looking for somewhere else.

“It was a lucky day for Kokura.”

She smiled. “I shall always remember being 12.”

At the western tip of Japan’s western Kyushu island, Nagasaki is located at the head of a narrow bay where the Nomo and Nishisonogi peninsulas meet.

Before the arrival of the Portuguese in 1571, Nagasaki was the principal port of call for foreign ships. Christianity was introduced through Nagasaki by Roman Catholic missionaries.

After 1636, during “the great exclusion” of foreigners, Nagasaki became the only point of contact with the outside world.

Only the Dutch were welcome and they were only permitted to stay on Deshima island.

The Atomic Peace Park is, unsurprisingly, Nagasaki’s biggest attraction.

Every day parties of schoolchildren and busloads of mainly Japanese tourists line up in front of Seibo Kitamura’s giant peace statue and smile for the cameras and camcorders.

They have special grandstand for such snapshots.

I come here to breathe in hope and feel freedom

“The folded right symbolises quiet meditation. The left leg is poised for action in assisting humanity,” the brochure told me about the statue’s symbolism.

An inscribed stone beside it the statue explained a little more.

“One resting arm signifies peace and the other is lifted to the sky, pointing to the threat of nuclear war.”

Visitors leave wreaths and candles at the temple where the ashes of 8,927 victims sleep at peace.

They visit the shrine to the unidentified victims from “that unimaginable day”.

They remember the survivors of “the bloodcurdling carnage”.

Students write essays in the Aspiration Zone, a special place dedicated to thinking about the future.

Old men come to meet and to talk. One was drying his socks in the sun. An old lady in a cloche hat sat under the peace fountain.

“I come here to breathe in hope and to feel freedom in my face,” she said.

Near the museum is a black stone commemorating the exact spot – the hypocentre – above which the bomb was detonated.

A five-foot sign marked the original ground level. Two-and-a-half square miles of the Matsuyama-machi district of Nagasaki were levelled in 1945. Fifteen thousand houses disappeared in one blinding flash. Seventy-four thousand were killed.

There is less hurly-burly in Nagasaki. I walked up to the Urakami Cathedral, once the largest church in the Orient.

It was destroyed in by the atomic bomb and rebuilt in 1959.

I started talking to two bow-backed nuns, who suggested I take the aerial ropeway up to Mount Inasa.

After that, again following their recommendations, I visited the site of the martyrdom of 26 saints, six European missionaries and 20 Japanese Christians who were crucified for their beliefs in 1597.

I then visited Dejima, built to isolate the morally dangerous Europeans or ‘Hollanders’.

Nagasaki also boasts the Glover Garden, inspiration for Puccini’s Madame Butterfly, and ‘The Spectacles’, the oldest stone arched bridge in Japan.

An hour away by train along the coast is a memorial to another modern horror and a symbol of what mankind can do to itself – the Huis Ten Bosch theme park, a miniature Holland in Japan, complete with windmills, tulip fields, canals and everything else you would expect from a Low Country, except a red-light district and relaxed cannabis laws.

The food in Nagasaki is as good and as cheap as anywhere in Japan with Shippoku, the local cuisine. This is a large, multi-course banquet consisting of about 30 different bowls of food.

You can eat as much as you like, until either you or your credit card explodes.

But easily the best a thing I ate was my ice cream in the peace park. I went back to get another one. Mrs Nakata recognised me and gave me it for free.

“Oishii desu,” she said. That means delicious.

I returned her peace sign.