TWO members of the Joint Association of People's Organisations for the Promotion of Democracy unfurled protest banners in the public gallery while Mr Patten was making his speech yesterday. Li Man-yeung and Luk Fuk-shan had hidden the banners, with white Chinese characters on a red background, inside their clothing. The banners called for a referendum over the political future of Hong Kong. Surprised Legco President John Swaine yelled ''stop that'', while Mr Patten halted his speech before commenting that the protesters had made good use of ''visual aids''. The protesters were led out by security officers and warned that they might be prosecuted. ''I know that I might be prosecuted, but I wanted to let both China and Britain know that they should not betray Hong Kong people,'' said Ms Luk.