WHEN it is defending an entrenched position, the Government has a sharp tongue and even sharper elbows. It is not so long ago that opponents of the plan to dump Hong Kong's sewage in the South China Sea after only primary treatment were being dismissed as 'media, academics and amateurs' - as if such people could not possibly be better informed than Government planners. However, now that a panel of three independent experts has come to much the same conclusion as the amateurs, the Government is at least changing its position with good grace. Officials who were previously reluctant to recognise that sewage treatment technology had progressed significantly in the years since their plans were first formulated, are now prepared to listen to wiser counsel. The chemical treatment recommended by the expert panel will leave the harbour cleaner sooner than the previous lime treatment. And the remote outfall, planned for the second stage of the scheme, can now be located in the Lamma Channel instead of off the coast of Zhuhai. That will save time and money and yet accelerate the improvement of Hong Kong's beaches. The scheme does not go far enough for environmentalists who hoped for a series of smaller, more widely dispersed outfalls instead of a single point of concentrated discharge. But it is a vast improvement on the previous, ethically and environmentally questionable plan to dump the territory's sewage in Zhuhai's back yard. It is doubtful whether environmentalist concerns alone would have been as persuasive as Chinese opposition, in persuading the administration of the error of its ways. But the Government should be given credit for listening to public opinion, however belatedly and reluctantly. The experts have provided an elegant and convenient ladder to climb down. It is now up to China to recognise the spirit of compromise in which the Government has accepted their advice.