IT wasn't on the agenda, but it was on the pavement outside Legco. It might even have been a new movement: an exhibition of document art. Its title? ''Recycle the Pink Book: Response to the Arts Policy Review.'' Rarely can so many government documents have been put to such splendid use. Some had been ripped apart and made into paper boats. Some had been defaced with popsicles in various decorous states of thaw; one carried a picture of Christ and his fellow crucifees on Calvary, clearly a reference to what the Government was doing to artists. Who needs Legco with such means of self-expression? Well, Emily Lau Wai-hing, for one. She looked as if she wanted to do something similar to the Chief Secretary after he left her confused and clearly a little miffed with a reference to Lord Howe. Plain Sir Geoffrey, as he was then, had told the Foreign Affairs Select Committee that part of Britain's responsibility would be to mobilise the widest possible international help for people desperate to flee Hongkong. Miss Lau, who seemed to think this was an evasion, pressed Sir David to explain Britain's other obligations to ethnic Chinese British passport holders. Sir David repeated his point. Christine Loh Kung-wai tried again. Would the Chief Secretary answer the other half of Miss Lau's question? But Sir David defended himself with an answer about oral hygiene. ''It's not for me,'' he said, ''to put words in the mouths of ministers of Her Majesty's Government.'' Another man clearly shocked by the moral implications of suggestions from Legco's liberal fringe was the Secretary for Planning Environment and Lands, Tony Eason. The perfectly respectable former missionary Elsie Tu started the ball rolling with a question about the Government's efforts to prevent Housing Authority tenants sub-letting their flats or using them for non-residential purposes. The affable Mr Eason replied that piano lessons, childcare and other inoffensive activities would be tolerated, so long as the flats were also lived in. However, a detection team had been set up to track down the real baddies with such draconian methods as surprise raids outside office hours. (''What? Civil servants? Never!'' someone whispered rudely from the press gallery.) But then Housing Authority member Frederick Fung Kin-kee, filled with cultural revolutionary fervour, suggested fellow tenants could be paid to snoop on their neighbours and report abuses. Mr Eason had to have the question repeated before the full importof Mr Fung's idea sank in. ''The idea of my neighbour creeping around my flat and reporting to the manager of my estate as to what I'm doing fills me with a degree of abhorrence'' said Mr Eason, when he had regained his composure. But then, he added mischievously, perhaps it wasjust the kind of suggestion he should be putting to the Housing Authority. A few members sniggered. After all, the Patten administration regularly out-liberals the supposedly liberal Mr Fung. But if others wondered what Mr Eason might be getting at, the even more terribly liberal United Democrat HA member Lee Wing-tat soon made it clear: Something strange happens to liberals when they join the HA. Mr Lee wanted to know why emigration records and Buildings and Lands Department files could not be checked to find out which tenants had moved out and were subletting their properties? ''So long as we are asking the Housing Authority to lead us gently down the path towards a police state, I'm sure that this kind of idea can be considered,'' ventured Mr Eason, kindly. Next thing we know, new HA chairman Rosanna Wong will be beating a path to Beijing's door too.