Just because there's been no announcement doesn't mean that nothing is happening.
Absolutely right, you never know what is happening behind the scenes. It may well be that the main reason for the Chinese Premier's visit to Manchester is to re-announce the stuff that Osborne has already announced. Again an air service between an insignificant city in UK and Beijing may not warrant his mention (for a domestic Chinese audience).
And no, I'm not casting aspersions on Manchester as a city, just suggesting that on a global (and Chinese public's perception) scale it isn't that important. Neither are any other UK cities outside London.