WITH 70 newspapers and 600 magazines, the Hong Kong press is both free and diverse. In theory, that freedom and diversity ought to mean that a change of control at the South China Morning Post was a matter of no great concern, whatever the plans of its new boss, Mr Robert Kuok Hock Nien. For if Mr Kuok did seek to change the Post in ways which the public did not like, then over time the Post would lose circulation, Mr Kuok would lose money, and other newspapers would manoeuvre to fill the gap in the market. In practice, of course, life is not so simple, especially in the present climate. The Post is an institution which so completely dominates the English language newspaper market that any serious challenge would require years of effort at the risk of hundreds of millions of dollars. At the first board meeting after the sale, Mr Kuok acknowledged that in buying a significant interest in the Post that he was ''aware of the [Post's] enviable position in this part of the world''. With control of the Post, Mr Kuok has acquired a powerful franchise entrenched enough to hold its ground well beyond 1997, however its editorial content might evolve. And after 1997, the Hong Kong media market may well be very much less open to new competition. Some suggest that Singapore, Mr Kuok's former home base, with its highly restrictive press-licensing regime, may be China's model. For his own part, Mr Rupert Murdoch was reported to be happy to sell control of the Post to Mr Kuok because he was ''clearly increasingly nervous about the difficulties of running a daily newspaper once Hong Kong reverted to China's control in 1997'', the London Financial Times reported on September 4. No doubt Mr Murdoch's attention had been drawn to Article 27 of the Basic Law, which promises ''freedom of speech, of the press and of publication'' after 1997. But perhaps Mr Murdoch had also noticed that Article 35 of China's constitution also promises''freedom of speech and of the press'' to all citizens. And perhaps he had concluded that Chinese-style ''freedom'' was not what it is made out to be. Mr Murdoch's retreat is worrying, then, for what it appears to be saying about the prospects for press freedom beyond 1997. And it is doubly worrying since News Corporation was a professional media group which understood the virtues of running the Post with minimal editorial interference. I T is hard to predict with certainty what Mr Kuok's editorial intentions towards the Post may be, since his interest in newspapers has been seemingly focused on keeping his own name out of them. But he has staked much of his Kerry Group's fortunes on investment in China, and he has agreed to serve as an adviser to the Chinese Government. We now know, from Xu Jiatun, the former Xinhua Director's memoirs, that in the 1980s, he had considered buying the Post through a local businessman. In those circumstances, and given China's manifest desire to influence public opinion in Hong Kong, it would be naive to imagine that the Post transaction was without political colouring. It would be equally naive, however, to imagine that Mr Kuok, one of the cleverest and most far-sighted businessmen in Asia, can be any very great admirer of the ideology and the practices of the Chinese Communist Party, however politely he may behave wheninvited to the Great Hall of the People. Perhaps his real gamble in buying into the Post is that he sees China on the verge of enormous social and political change, and that huge opportunities for independent media will be created not only in Hong Kong but across China. If so, one can only wishhim success.