WHERE is William Tang? ''Sorry, he's somewhere in Asia,'' said an apologetic voice at the designer's Central showroom yesterday. ''William headed off before Christmas and he's been to London, New York, Toronto - all over the place. He's recharging his batteries.'' Not in time for Hong Kong Fashion Week '94, which kicks off today and runs until Saturday at the Convention and Exhibition Centre. For once, Hong Kong's premier fashion event will have to do without Wicked William and his unpredictable bag of tricks and, so for that matter, will the Hong Kong Fashion Designers' Association (HKFDA). Last year, the organisation which boasts the most prominent names in local fashion had a field of 10, including Tang. This year, seven will be showing and it all sounds very politically correct. ''Prompted by such concerns as pollution and dwindling natural resources . . . this year's theme [is] 'For The World, Be The World' to express environmental awareness through fashion,'' reads a solemn press release from Fashion Week organiser, the Trade Development Council. The more exciting news from the TDC is that this year's fair is the biggest ever, with a record 850 exhibitors - nearly a third of them from overseas - taking part in the four-day event which has no rival in the region. More than 28,000 fashion buyers and traders from all major markets around the world are expected to register at the Wan Chai waterfront venue. So what can they expect? Smooth organisation with none of the chaos of the bad old days, if last year's impressive performance is repeated. Also far more space: for the first time, three levels of the Convention and Exhibition Centre have been allocated to Fashion Week instead of the usual two and, hopefully, some exciting shows. The days when individual fashion houses and firms staged their own extravaganzas appear to be over. ''Prohibitively expensive,'' said a leading designer last year. Now it's all group shows: Designers' Collections I and II, Knitwear, HKFDA, Hong Kong Labels, Casualwear Specialty and, biggest drawcard of all, the Young Designers' Show. Heading the panel of judges at the YDS on Saturday night will be Italy's Romeo Gigli, by far the most impressive name to grace the contest in years. ''We're thrilled to have him at Fashion Week,'' said a TDC spokesman of the Florence-born designer whose first collection, in 1986, was an instant hit and who has stayed at the top with his couture and ready-to-wear lines for women and men. Also reflecting Fashion Week's internationalism will be a small but impressive contingent of journalists from major overseas fashion centres including Paris, London and Milan. The biggest national pavilion after the territory's will be that of China whose presence will also be reflected on the catwalk. Among the mainland beauties showing off the best of Hong Kong fashion will be Zhou Jun, winner of the China Supermodel '93 quest and Li Hua, winner of China's first Fashion Model Contest held in Dalian last year. Performing the opening honours at Fashion Week this morning will be deputy to the Governor, Chief Secretary Anson Chan. A conservative but stylish dresser who favours updated cheong sams and classic suits, Mrs Chan can expect unusual scrutiny from the press as she cuts the ribbon.