With respect to bill structure compare Neil's bird with this Verditer:
http://orientalbirdimages.org/se ... _ID=&pagesize=1
and with this Pale Blue:
http://orientalbirdimages.org/se ... _ID=&pagesize=1
Even accounting for possible subspecific differences in Pale Blue bill structure, I still see no reason that this bird is not a verditer. Bill structure and plumage both look exactly like female verditer and in my opinion do not fit pale blue (look especially at head pattern and underparts colour compared to the bird I have linked).
For some reason one of these birds gets reported almost every year as a pale blue and every year we go through the same arguments and eventually reach the conclusion that it's a female verditer. For some reason there seems to be a belief that pale blue 'must be occurring in Hong Kong in winter' based on an old record of a bird singing in spring. There has (as far as I am aware) been no claims of females, even though these appear from photos to be relatively distinctive (not as difficult as other female Cyornis, and at this time of year most Hainan Blue have migrated so any female cyornis should stand out).