Originally Posted by
orbitmic
I may be totally wrong on this, in which case I do apologise, but I thought that the visa-free transit was only available when arriving from an international flight departing to an international flight to a different country within the appropriate period (72hrs at most airports, 144 in some like PVG), ie not valid if you have to take a domestic flight. Is this not the case?
That actually was the point I was making in the first paragraph: the OP originally said CAN, then said "from Chengdu", and we don't know if it's LHR-CTU-HKG (potentially OK for visa) or CTU-CAN-PVG (not OK unless other flights are involved).