MAN-PEK-PVG would be competing with MAN-DXB/DOH/LHR/CDG/MUC/ETC-PVG so to gain a decent cabin load on the initial MAN-PEK sector could need a fairly hefty price decrease and then the yield on such a long route comes into question.
Via DXB (or DOH) is one hell of a long way round, almost 1,500 mi. longer than via LHR. Via HEL is almost 200 mi. shorter than LHR. Maybe AMS and FRA and HEL should be on the list. Needs to be a lot cheaper for the extra 1,500 mi., else it's a triumph of marketing.
Great Circle Mapper=
Yield wise, MAN is the ideal candidate for a tag-on, and then if this is the case, unless MAN is the intermediate stop (such as LIS-MAN-PEK), you are effectively the poor cousin of intra-China connections as you already have the disadvantage of being 2 stop over those carriers offering 1 stop to the larger Chinese cities.
Do you mean a MAN as a "tag-on" such as SIN-MUC-MAN?
Again it's a question of fares, LIS-MAN-PEK on a Chinese carrier as opposed to LIS-(change at) LHR, AMS, CDG or FRA-PEK on BA, KL, AF or LH respectively.
Can MAN sustain a service to China? I would say yes, however that might best be Hong Kong for connectivity rather than the mainland. It remains a mystery why Cathay is alway "soon". If Air China can afford to run a thrice weekly Gatwick service, perhaps couple the other four days to MAN, the A330-200 is the right size for an entry level service.
It all depends on how succesful the initiatives to improve trade and business links between the two countries turns out to be. We need to grow links with up and coming countries, and diversify.
We cannot rely on the majority of trade links being with the eurozone, it is unsustainable in the long term and has major problems which will not be resolved any time soon. The UK has to diversify its trade links and China is a reasonable place to start.
Certainly agree that HKG is probably the best place to start with, but it has to be Chinese carrier, as BA (apart from HKG with CX) or VS do not have the network of transfer opportunities at the China end, both within in China and beyond. At the UK end, BA and VS funnel transfers pax through LHR.
For example, a Chinese carrier could also offer flights "down under" with one change of aircraft, and/or the possibilities of a stopover somewhere different. China is introducing visa on arrival for short stays so this will become increasingly easier. For HKG, visas are not needed.
The carrier that takes on the route would determine whether the destination in China is HKG, PVG, PEK or CAN.