BRITAIN'S new senior Trade Commissioner for Hong Kong arrives today to prepare the ground for the United Kingdom's presence after 1997 and especially to demonstrate that its interests in the territory will continue to be considerable. Francis Cornish, formerly Foreign Secretary Douglas Hurd's press secretary, says he will not become involved in the negotiations with China over democracy or play a political role. ''As far as the negotiations are concerned I have no part in them. I shall watch them with a keen interest.'' Nor does he believe there is any evidence to suggest discrimination against British companies in China because of differences over the democracy proposals, citing GEC-Alsthom's success in winning the contract for Guangdong's Shajiao power station. Mr Cornish, who arrives with his wife June today was last in Hong Kong in the summer when he came with Mr Hurd after his Beijing meetings aimed at injecting more pace into the democracy talks. He will lead the British Trade Commission up to 1997 to prepare it to become the British Consulate-General following the transition to a Special Administrative Region. But he said he did not know if he would be the man to fill the post of Consul-General.
