I think I tripped up on the common names, melding them together. Different sources have it as Red-flanked Bluetail; Orange-flanked Bush Robin; Northern Red-flanked Bush Robin. I was sure I had found it somewhere under the name I used, but now can't find it, so probably just mixed them up. At least here they are orange not red. I got the scientific name correct though! Tarsiger cyanurus.
Still toughing out the wait for my Birds of East Asia. Had another new one to me today that I was sure would be easy to figure out but for the life of me I am not finding. I am sure is perfectly obvious to those of you familiar with birds of NE China.
Also had two showing bright blue and white but which were moving very fast and tangled up together in close combat. Only a quick glimpse as they zoomed out of the village, overhead and across the pond into trees.
Hopefully a better look next time. Fast enough and the right size and general shape that they may have been swallows, maybe Barn Swallows?