THE deteriorating position of British Prime Minister John Major must be adding to the worries of Governor Chris Patten. Mr Patten is not only one of the Prime Minister's most trusted advisers, he is a close personal friend. Only last week Mr Patten was, asis his manner, outspoken and vociferous in support of Mr Major. He paid tribute to Mr Major's achievement in winning an election in the middle of a recession - a poll that cost Mr Patten his own seat in Parliament - and expressed confidence that Mr Major would lead the Conservative Party into the next election. Though the uncertainties of British politics mean it would be unwise to write Mr Major off, Mr Patten's confidence in him is looking increasingly optimistic. Last week's debacle over the European Union - when Mr Major talked tough to woo the Euroscepticson the right of his party, then sacrificed credibility when he failed to deliver - is the latest in a series of missteps that have combined to make the Prime Minister appear inept. The latest opinion polls, indicating Mr Major is becoming even more of a liability for the Conservatives, mean the prime minister is likely to be knifed in the back if he fails to fall on his sword. The good news for Hong Kong is that none of this is likely to increase uncertainties in the territory appreciably. Mr Major's most likely successors - President of the Board of Trade Michael Heseltine and Chancellor of the Exchequer Kenneth Clarke - are both, like Mr Patten himself, viewed as being on the left of the party. And even if a right-winger such as Chief Treasury Secretary Michael Portillo gained power, Hong Kong is not enough of an issue in London to prompt a fresh change of direction. As forMr Major himself, to quote Macbeth, ''If it were done when 'tis done, then 'twere well it were done quickly.''