It's exactly 50 years since the famed Summer of Love when the "Turn on, tune in and drop out" generation shed their clothes, put flowers in their hair and, at festivals like Woodstock, overturned prim morality and ushered in a sexual revolution that would soon make its influence felt around the world.

During that summer, the 27-year-old John Lennon — already married — decided to lend his support to the London exhibition of a Japanese artist called Yoko Ono, and pretty soon the world's most famous Anglo-Japanese union was created.

Such cross-cultural marriages may have been pioneering in the late 1960s, but these days they are overwhelmingly commonplace. A couple of years ago, when I was promoting a book on Yukio Mishima, I was interviewed in London by a Japanese journalist who suddenly asked me whether I too had a Japanese wife. When I told him that my significant other was Australian, he laughed at my eccentricity and remarked that in his experience, 90 percent of Western male scholars of Japan, when they had a wife, tended to have a Japanese one.