More by a process of elimination than anything else, I think this bird is probably a Hill Blue Flycatcher. There is a lack of contrasting pale throat against the colour of the breast (which this bird exhibited, and which I am now confident is a "Chinese Blue", the former glaucicomans race of Blue-throated). Cyornis flycatchers are a real challenge to ID on migration, and today's little skulker was no exception.
The other main highlight of the morning was a flock of 10-15 Blue-throated Bee-eaters, a new bird for the patch. Blue-throated is a relatively common migrant and a bird that I've been expecting, so it was great to finally connect with a rather showy group that passed through the park, stopped to feed and then carried on south.
A study in blue
There was a nice variety of other migrants around including the first Taiga Flycatcher and Black-capped Kingfishers (2) of the autumn, two Pale-legged Leaf Warblers, Eastern Crowned Warbler, two Plain-tailed Warblers, five Asian Brown Flycatchers and several Brown Shrikes.