MANFOD,
In reality I don't think the demand of any 1 city outside of London would be enough to sustain a China service, it would have to be aimed at all of the major cities, as you say there is a large Chinese community in Manchester, there is the traditional tourist attraction of Liverpool and then there are the large business links between Brum and China. I'm sure Leeds and Sheffield will also have their links, for this reason MAN would appear to be the central Airport of the 5 cities. These flights ran last year from BHX and from memory were a sell out so it was odds on a repeat of some sort was on the cards, a massive leap though to go from a short run of charters to any long term scheduled service.