I am NO friend of China - indeed I've always favoured giving recognition to democratic Taiwan rather than the autocratic mainland. However, when this was all set up, you must remember that HMG were all over China, promoting trade as being the way to encourage liberalisation.
Xi Xin Ping was being bought pints in the pub near Chequers, George Osborne and David Cameron were visiting Beijing, and we were all being encouraged to view China as a valued partner and potential friend. Those who set this up were no doubt encouraged to do so.
One can only imagine that the flow of intelligence from China must have been useful, while hoping that those involved were smart enough not to give away anything that they should not have done.