AS China turns the screw in its attempt to force Britain to back down over the Governor's political reform proposals, concern is growing over how the local economy will be affected. A freeze on meetings of the Joint Liaison Group threaten progress on several fronts. As the Provisional Airport Authority Chief Executive Dr Hank Townsend pointed out earlier this week, there have been no delays in the development programme just yet, but it can only be a matter of time. A similar worry exists as a result of China's refusal to name a date for the next meeting of the Sino-British Land Commission. With the major exception of the land for Container Terminal 9 (CT9), which is already caught up in the political row for other reasons, short-term hold-ups cause more damage to confidence than to construction work or the sale of property. China Light and Power, awaiting approval for the release of 46 hectares for its Black Point project, has several months leeway before it needs to begin building. Property developers say they have title to sufficient land to keep them going for two to three years ahead. Many of them also have considerable opportunities over the border, should the local market prove more difficult than expected. Meanwhile, the Housing Authority foresees no problems for another 15 months at least. Its public housing estates are on Government land, which requires no referral to the Land Commission. Home Ownership Scheme units for sale in the coming financial year have all the necessary documentation. However, hold-ups in the Land Commission are bound to begin to bite elsewhere. Using it as a lever could undermine the very projects Beijing has already singled out for criticism. Mr Patten has been accused of ''pressurising China'' by publicising the sandwich class housing scheme without first raising it in the Land Commission. Sure enough, the Government is now forced to admit that no construction can begin on the project until China agrees to release the land. China's attacks on CT9 have held up formal agreement on the project to such an extent that it is now about to return to the Land Commission agenda. The release of land for the port development was originally approved by the Commission a year ago in the programme for the 1992/93 financial year. That was once the Hongkong Government's main argument for claiming it could go ahead without further approval from China. Now, unless agreements with the operators are formalised by next week, the disposal will have to be re-approved for 1993/94. At first sight, China appears to be harming its own interests. Under the terms of the Joint Declaration, 50 per cent of the revenues from the release of Government land accrue to the future Special Administrative Region Government. The Director of the Hongkong and Macau Affairs Office, Mr Lu Ping, is already rubbing his hands in anticipation of the $80 billion he estimates will be in the SAR Land Fund by 1997. On the other hand, China may feel that it stands to lose nothing by delay. If the market dips while London and Beijing remain at odds, it will certainly soar the moment the political row is resolved. Delay could therefore boost the SAR's share of the profits. The Hongkong Government, which is relying on its half of the forecast $24 billion land premium income for a hefty slice of its 1993/94 budget revenues, will bear the consequences. If that theory held true, the Governor's Achilles heel would be exposed. Since it is the Government rather than business which would feel the pinch first - and the taxpayer who will be asked to foot the bill - Beijing would have found a way of undermining support for Mr Patten. Predicting the course of the Hongkong property market is not an exact science, however. A Land Commission standstill, instead of triggering a fall in values, could provoke a speculation-driven rise, based on popular belief in a land shortage which would affect new development. Property stocks on the Hang Seng index have remained resilient, if prone to fluctuation. Faced with such uncertainties, property owners large and small must wish that both sides will recall their commitment in the Joint Declaration to maintain the territory's stability and prosperity. If Britain and China could only regard July 1, 1997 as a window of opportunity rather than a door to be closed - which may seem a vain hope at present - they would not be risking damage to the job of building its future.