A LAWSUIT has been filed against the Governor, Chris Patten, by a man who claims Mr Patten's broken promises led him to lose a bet. Kwun Tong resident Philip Lam Yung-tak claims he bet that a counter-proposal he submitted on the electoral reforms would be included in the compendium of public responses on the package. He said he had in mind Mr Patten's claims of ''truthfulness and fairness and his friendly invitation and announcement that the proposals will be published'' when he made the bet with a businessman friend he refers to as Mr Lau. He does not say how much the bet was for. But when the compendium was published in January 1993, Mr Lam's proposal was omitted and he says he has been ''misled by the announcements and introduction of the first defendant''. Mr Lam is seeking compensation for his loss, and is also asking Legislative Councillors to vote to suspend the partial electoral bill, and set aside the compendium. The former secretary for constitutional affairs, Michael Sze Cho-chueng, and the Legislative Council are named as second and third defendants, although no allegations are made against them. Last night, a government spokesman denied the claims. ''The Government will take immediate steps to the court to have the application struck out as an abuse of process,'' he said. Mr Lam also challenges statements made by Mr Patten that China and Britain had agreed to nothing more than the lowering of the voting age to 18 in the 17 rounds of Beijing talks which ended in November.