'AFTER 1997 there will be a big change in social attitudes. As far as sex is concerned, it will be for the better.' Those were the words yesterday of Dr Ng Man-lum, also known as 'Dr Sex', who believes the departure of the colonial regime will mean that at last Hong Kong can start talking seriously about sex. The vice-president of the Hong Kong Sex Education Association was explaining yesterday how the 1999 World Congress of Sexology could be held in a territory that just a month ago decided that New Man and Michelangelo's David were indecent. 'By that time the British will be gone,' he said, noting with approval that in China sex education is compulsory in primary schools and serious sexologists are respected by the Government. Leading sexologists in China would be able to show their findings to the world at the conference, and Dr Ng said that the four-year gap before it started would allow time for research into Hong Kong's sexual habits, about which relatively little is known. For the 1,000 sexology professionals expected to attend the event, to be held in the conference centre in 1999, the highlights will include seminars and workshops on every form of sexual activity plus the presentation of the sexology world's equivalent of the Nobel Prize. Dr Ng also promised events for the public such as exhibitions of sex art. 'And if there are any protests, it will still be a good thing - it will create big interest,' he said. The World Congress of Sexology, which has just finished in Japan, included a collection of sex relics that had survived the Cultural Revolution in China. Although much of the conference material was explicit, little of it could be described as erotic. The professional papers included 'Folk Poetry Against AIDS' and 'Colour Doppler Papaverine Test'. When details of the conference were announced at the university yesterday, the only time the word 'penis' was used was when Dr Ruben Hernandez-Serrano, president of the World Association for Sexology, talked about the 'bombshell' of the Japan conference - a treatment for male infertility using a plastic insert - which he demonstrated using the straw from a container of soya milk. 'This is a real medical profession,' said Dr Hernandez-Serrano.