UNITED Democrat Lam Wing-yin has been elected to the Regional Council with 4,670 votes after beating six other candidates in the scramble for the seat vacated by convicted councillor Gilbert Leung Kam-ho. Mr Lam's victory marked the end of the conservatives' domination in the Sai Kung constituency. It also strengthened the liberals' influence in Regco by bringing the number of United Democrats to six. The pro-China Democratic Alliance for the Betterment of Hong Kong (DAB) was beaten into second place in Sunday's poll, with its candidate, Cheung Hon-tin, getting 4,016 votes. Both Mr Lam and Mr Cheung, the first candidate fielded by the DAB since its inception last year, finished more than 1,300 votes ahead of the other candidates. The vice-chairman of the Association for Democracy and People's Livelihood, Law Cheung-kwok, came third with 2,657 votes - another defeat for him after the 1991 Legislative Council election. He was followed by independents Francis Chau Yin-ming and Wong Shui-sang with 2,312 and 2,017 votes respectively. Meeting Point's Wai Hing-cheung managed to get 552 votes and Liberal Party member Wong Wah-keung secured 475 votes. Reports that the United Democrats were in decline had been disproved by the result, said Dr Stephen Tang Lung-wai of the Chinese University. However, he said the party should start searching for stronger candidates to continue its success in the 1994/95 elections. Although the DAB was quite close to its liberal rival, Dr Tang said the result indicated that many voters still had reservations about pro-China candidates. Political analyst Citi Hung Ching-tin described the by-election as a dress rehearsal for the 1994/95 elections. Political analysts expect a landslide victory for the United Democrats but Mr Hung predicted it would be a two-horse race. The Regco poll was further evidence that the rural influence was on the decline, he said. The success of Mr Lam was attributed to his party-affiliation, which boosted his popularity among residents of Tseung Kwan O, from where most of his votes came. According to Dr Tang, the participation of political personalities such as Martin Lee Chu-ming, Szeto Wah and Emily Lau Wai-hing played an important role in Mr Lam's success. ''The victory of the United Democrats is a surprise. It had so little influence in that area before the election,'' he said. Mr Lam admitted that the party had played a crucial role in his election campaign, but dismissed the suggestion that the party could win regardless of who was fielded. The 34-year-old accountant said he would resign from his job to fulfil a commitment he made to the party before joining the election. He will help to set up a district office for the United Democrats and a Regional Councillor's office in Tseung Kwan O to deal with the complaints handed to him during his campaign.