CHINA DIARY By Stephen Spender and David Hockney (Thames & Hudson, $220) A RE-PUBLICATION of a 1982 travel book on China sounds about as unappetising as a cold plate of last week's Peking duck. Not so this new paperback edition of China Diary. When, in the early 80s, American tourism to China was in its infancy, China Diary quickly became favourite reading for discerning travellers. There is little reason why it should not remain so. Granted, events in China have overtaken the book in some ways, occasionally making it read more like history than travelogue. In 1981, Sir Stephen Spender and David Hockney show a clear preference for socialist China over capitalist Hongkong. Twelve years later the people of China have decided otherwise; they are opting for Hongkong ways, warts and all. China Diary is no longer simply a brilliant travel companion; events have propelled it into a telling historical and social commentary. It may be still true that ''in China today officials live in apartments more hidden from the public gaze than those of any Emperor and his retinue in the Forbidden City'', but Spender could not now write ''To many Americans, China is a love-object. . .''. Nor could he report that ''property of foreign visitors is meticulously guarded''. China Diary is a constant, valuable reminder of just how much change there has been. The observation of Spender's pen and Hockney's camera and brush are very keen. The result is an intimate view full of close observation. How true it is that many Chinese speak English ''with a kind of eagerness as though pleasurably reaching forward for each next word''. How understandable it is that Hockney's favourite place was Guangzhou's Children Park. Beijing, which left Spender with ''an impressionless impression'', is today even more ''a vast grey dusty vague area'' than it was during their 1981 visit. The city has more of the buildings that resemble ''columns of tanks lined up in a desert''. The Great Wall remains ''the apotheosis of the idea of China'' being more remarkable as an idea than as an object. Hangzhou's enchanted West Lake remains ''that mixture of nature and artifice, one century and another, past and present, so bewildering for the foreign visitor to China.'' Spender's final memories were prophetic. Commenting on the ''natural goodwill and friendliness'' of the Chinese, he also noticed that ''the Chinese like being small traders'' and that under their drab uniforms there lay hordes of individualists. A return visit today would no doubt find the Chinese personality little changed but they would be aghast at the progress of the ''worse-than-Disneyland vulgarity'' that they came across in 1981. Freshly-written travel guides to China (there is never a shortage) usually lack those qualities with which China Diary is brimful. Here there is Spender's superb, expressive control of language, packed with an acute insight that brings out the essential character of the Chinese. Hockney's many splendid photographs and sketches round off a book that still ''works''. Be put off by that original 1982 publication date and miss it all.