The democratic camp's candidate, barrister Audrey Eu Yuet-mee, was heading for victory in the Hong Kong Island Legco by-election last night, according to an exit poll. The poll, conducted by Dr Robert Chung Ting-yiu of the University Hong Kong's Public Opinion Programme, showed Ms Eu with a lead of about 20 percentage points over main rival, district councillor Christopher Chung Shu-kun of the Democratic Alliance of the Betterment of Hong Kong. The margin of error was 4.5 percentage points. Ms Eu said she was happy with the projected result. 'If I really win, that'll be a good foundation for future [democratic camp] co-operation.' Mr Chung said he was at ease with the situation. The final turnout was 33.27 per cent, or 208,672 voters, compared to 42.03 per cent in the September election. Secretary for Constitutional Affairs Michael Suen Ming-yeung said he was 'a little disappointed'. But he said there was a critical mass of more than 30 per cent of the voters 'who turn out to vote every time'. This underlined the formation of an election culture that would be important for Hong Kong to push ahead with constitutional changes. Analysts had regarded the turnout for September's Legco election as poor, but said they had expected yesterday's figure to be even lower than it was. Chief Executive Tung Chee-hwa, after casting his vote with his wife at the Hong Kong Park Indoor Games Hall in Central, said it was common to have a lower turnout in by-elections. 'It is the experience across the world,' he said. 'The Government has done lots of work. Just on promotion, $3.7 million was spent.' Commenting on the low early turnout, Electoral Affairs Commission chairman Mr Justice Woo Kwok-hing said voters might have remained in bed. 'Unlike the summer, people like to stay in bed longer on cooler days,' said Mr Justice Woo. The seat was vacated by former DAB vice-chairman Gary Cheng Kai-nam, who was forced to resign after being returned in September. He admitted failing to declare to Legco his interests in a public relations firm and leaking a confidential document to a business client. City University social science lecturer Ivan Choi Chi-keung said the turnout was better than he had expected. 'For by-elections, there would be in general a 20 to 30 per cent lower turnout,' he said. 'The lack of celebrities running also made the election less attractive.' The other candidates were solicitor Paul Tse Wai-chun, district councillor Jennifer Chow Kit-bing, company director Shi Kai-biu and sales manager Simon Lo Ching-cheung. There were 228 complaints received by the Electoral Affairs Commission yesterday, most for illegal posting of election materials. The most serious complaint involved a campaign aide of Ms Eu - Democrat Lam Kee-shing - who was allegedly slapped by a DAB campaigner angry at the noise of Ms Eu's campaigning. DAB supporters also clashed with Ms Eu's election team shortly before polling closed. Emily Lau Wai-hing, of The Frontier, complained she was blocked by DAB supporters outside Siu Sai Wan polling station after she had helped with Ms Eu's electioneering.