A VISITOR from outer space who had the misfortune to bring his sputnik down in Central would probably have more urgent matters on his mind than working out obscure bird-feeding metaphors from Legco. Avoiding the traffic might be one of them. Not disappearing down holes in the road might be another. Still, once he had got his spacecraft to safety, he would probably have whipped out his Cantonese phrase book to find the words for ''Take me to your leader''. So, appearing in a speech by the Chief Secretary might seem almost natural. And sure enough, there he was. What would this little green man think, Sir David wanted to know, if after scanning the marvels of Hong Kong, he had then read a headline which accused the Governor of throwing a handful of crumbs to a flock of pigeons? Good question. What, indeed, might he have thought of Sir David? Or the rest of Legco, sitting in polite, impassive silence as an extra-terrestrial watched over the Chief Secretary's shoulder? Probably, Sir David imagined, the poor chap would have thought it a close encounter of a very curious kind. There was the Chief Secretary claiming to be tigerish, so that the Government should not appear a lame duck and being told by Elsie Tu to develop the skin of a rhinoceros. And as if that were not enough to confuse even the most intelligent life-form, Sir David urged Legco to assess the Government's ''progress in the round'' - without apparently meaning the whole administration was going round in circles. It might not have been obvious to our bewildered alien, but Sir David was socking it to Legco in his characteristically forthright and robust manner. What a bunch of old miseries they had been, carping at the Governor's speech instead of jumping for joy at its generosity. Businessmen who ought to have known better had asked for more government intervention while the rest of the crew had complained about the lack of commitment to the old, the sick, the poor, the police and just about any other deserving group you could think of. ''As we tennis players say,'' he smiled, ''never change a successful strategy.'' Other officials followed suit, lambasting Legco for being so negative. Some of them even looked as though they meant it. Secretary for Hong Kong Affairs Michael Suen Ming-yeung, on the other hand, appeared not to have noticed he had got out of bed. ''Vigorously, promptly and effectively,'' he mumbled, unable even to muster a yawn. However, Brian Chau Tak-hay, Secretary for Trade and Industry, was almost as feisty as the Chief Secretary. Especially on the subject of bureaucrats like himself, who were not as clever as businessmen and couldn't be trusted with industrial policy. They were especially unsuited to work out policies for the service sector because they could not tell what hamburger joints and maritime insurance had in common. But it was Transport Secretary Haider Barma who admitted the awful truth. There were too many cars and too many holes in the road. At that point the little green man took his eyes off the Chief Secretary's latest theatrical pose and smiled. Taking the magic wand from his space-suit, he directed the surplus vehicles into the surplus holes in the road. Then he beamed himself up to his sputnik and, like ET, he went home.