DEMOLITION work will begin tomorrow on Colvin House to make way for the construction of one of Britain's largest missions. The former venue for meetings of the Sino-British Joint Liaison Group (JLG) and the Land Commission will house the British Consulate-General and the British Council after 1997. It is understood that construction work carried out by British firm Terry Farrell and Co will take 21/2 years to complete and will be managed by Swire Properties. The future consulate-general and British Council will be housed in two curved 10-storey towers and will be staffed by 65 Britons and 370 locals. The three-storey Colvin House, in Admiralty, had served as the meeting venue for the JLG since 1988 before it was replaced by a site in Kennedy Road early this year.