GOVERNOR Chris Patten has warned of disruption and uncertainty if a set of clear and objective criteria on who can ride on the through train in 1997 is not in place before the 1995 Legislative Council elections. In an interview with the South China Morning Post, he gave a strong hint that London would prefer if lawmakers elected in 1995 could sit on the post-1997 legislature by taking an oath to uphold the Basic Law and swear allegiance to the Special Administrative Region, as prescribed under Article 104. ''Article 104 applies after 1997. All we're saying is that there should be similar criteria for determining candidates elected before 1997 can travel through after 1997. Article 104 is a good basis for determining the criteria for legislators travelling through 1997,'' he said. Mr Patten said the through train plus a set of ''fair and open'' electoral arrangements that were acceptable to Hongkong people were equally important to Britain. He dismissed speculation that London would make concessions on the pace of democracy at the expense of the through train. ''I think both pillars are equally important and neither are after all terribly difficult to achieve, or shouldn't be,'' he said. Mr Patten argued that there would be a ''complete distorting effect'' and disruption if subjective criteria were to be imposed when vetting legislators. ''Are the criteria going to be, for example, well we didn't like his opinions three or four years ago? Are the criteria going to be hidden in a smoke-filled room? ''At the moment, there are criteria. In order to be a candidate you need to meet certain qualifications. If you are a successful candidate and you win the election, again you have to meet certain qualifications, you must take an oath. ''Nobody can possibly object to there being criteria but we have to know what they are. ''I have never heard of an election where candidates do not know whether they will be in the entire period of the legislative body which is being elected. ''You write in the electoral address and say 'wait for me, I'd like to be around until 1999 but I'm afraid that I can't tell you whether I will be because it's all going to be dependent on the decisions to be made in 1996 on the basis which I don't know'. ''You only have to express the argument to see how absurd it is.'' Senior Chinese official Lu Ping told a Hongkong delegation last week that a set of criteria on the through train arrangements could be worked out by a working body of the SAR Preparatory Committee, which will be officially set up in Beijing on Friday. But he stressed that it was up to the Preparatory Committee itself, which will be formed in 1996, to confirm whether the lawmakers sitting on the 1995 Legco can continue to serve beyond 1997. Without a clear set of criteria on who could ride the through train in 1995, Mr Patten said ''the whole of the last two years from 1995 to 1997 of British sovereignty are going to be dominated by this question''. ''It would be disruptive of good government. It would be disruptive in the legislature. It would be, I think, a terrible backdrop to a successful transfer of sovereignty,'' he said. Not withstanding the differences between China and Britain on the constitutional talks, Mr Patten, however, was still hopeful that an agreement could be reached on the through train arrangements. ''I think if one actually talks through with a rational senior Chinese politician the points I've just made, they would not find it such a disturbing an argument,'' he said. ''Equally, is it such a disturbing argument to consider an election committee which is elected rather than selected? Is it so alarming for us to have functional constituencies which are substantial and represent interests which are important to the Hongkong community?''