No one is trying to play down the trauma of discovering what cheap novels call the 'betrayal' of a husband. But matters could be worse. Indeed they were much worse for Hong Kong women barely a generation ago.

At that time, in the tough post-war 40s, the nightmare of the Hong Kong wife was that she should wake up one day to discover that, far from being her husband's lawful wife, she had actually been the unlawful mistress all along, because he had already been married in his native village in the mainland. The 'mainland wife' was the nervous joke then, when communication had broken off after the communist takeover in 1949, and no woman could be sure of her husband's past.

From time immemorial Chinese men have left their homes in the village to seek their fortunes in the city. Reunions with loved ones took place only over long holidays such as the Lunar New Year. But then when these men were cut off - and it appeared permanently - from their families in the native village, there came a time when they believed they needed, and were entitled, to have a new family in Hong Kong.

THE Hong Kong women they married were hardly in a position to be overly scrupulous. In those days of scarcity, marriage was the only realistic means of livelihood to most women, and few could afford to pass up a man of seemingly decent habits and reliable income. And so the marriages took place, and most proceeded uneventfully. But to some, one day a letter would arrive, announcing that the man's wife and children were alive and well, and were about to join him in Hong Kong. Would he reject her? Or would he recognise her status? Such was the theme for many a Cantonese soap opera. In either event, the Hong Kong female partner could never feel the same again.

The phenomenon of mistresses has always fascinated, in the East or in the West. In the West it is perhaps simpler - or so it seems to a non-Westerner such as myself. If one is to believe the famous Hite Report, given that most men marry the women they feel safe with and desire the women whose looks excite them, mistresses are almost inevitable. The Western image of the 'mistress' is quintessentially sexually decadent. No wonder the idea of Chinese men with their concubines suggest to them a kind of licensed paradise of orgies.

But the Chinese mistress, or even concubine, is in reality a very different creature. In the imperial days not so long ago, concubines were often taken for face - it would be extremely eccentric, even scandalous, for a great man to have no concubines. Most concubines were little more than body servants with pre-approved sexual functions. Some concubines were taken the better to secure the line of succession, and so on. Many have grown respectable with age.

The Chinese mistress is often a surrogate wife. A wife, in the mind of the traditional man, is someone who looks after him. Someone who gives birth to his children and looks after them too. A regular source of comfort and support. Implicit, though unmentionable, is that she should provide him with that sense of security founded on reassurance of his own importance. Hence a wife must be pliant and submissive. For, it is in her submissiveness that he finds shelter from his insecurity, and the deeper the inner insecurity, the greater submission he craves. If he is deprived of such a wife, then he would look for a surrogate.

Thus the type of mistresses sought is not necessarily sexually glamorous, but the 'nice little woman', to substitute for a wife who is absent or who turns out not to conform to that image. In that sense it is true that the phenomenon of cross border mistresses arose out of need, either because the Hong Kong wife is absent when the husband seeks his fortune in some Chinese city, or because she is no longer able or willing to fit that bill.

However, it is not a need that deserves sympathy. Rather, the fact that there is such a need, and on such a scale (if impression unsupported by figures is to be trusted), is something about which one should be concerned. It signifies a social regression for Hong Kong. It also threatens to create social problems for the future.

It signifies regression in the sense that the development of a more equal relationship between men and women is progressive. Hong Kong has made progress in that direction since the post-war years, through education and economic development. Not only are women now in a far better position to attain financial independence, but this independence has become better understood and accepted. As more men became more intellectually sophisticated, they also became more appreciative of the independent woman. As it is no longer required for men's security that women be submissive, more mutually satisfying relationships have become possible - or so one thought.

THE phenomenon of cross-border mistresses gives one doubt. Perhaps this is telling us that while progress has been made in some areas, the community as a whole has somehow taken a great leap backward. A quarter of a century after concubinage ceased to be lawful, Hong Kong is now plunging back into the post-war era - without even the excuse of men being indefinitely separated from their legitimate families.

No doubt the cross-border mistress is a socio-economic phenomenon, rising out of the discrepancy in wealth between the Hong Kong male who frequent the mainland for business and the mainland female to whom being mistresses to these men is the easiest or the only way to obtain financial security.

Here is exploitation of the crudest and coarsest kind. These mistresses and their children, far more than the Hong Kong wives, should be the objects of concern and in many cases also of sympathy. Neither their nor their children's futures are protected. If they should come to Hong Kong, as eventually many of them will, their claim, however fraught with difficulties in law, must and will command the attention of a society with the least pretence to humanity.

Not so long ago, the question of Hong Kong's obligation to the mainland wives and children of Hong Kong men was raised, with no hint of a solution. It is ironic that mainland mistresses and their children may soon prove an even thornier problem, and a far more disreputable one.