Black Throated Tit?

I agree with Matthew, good record. The EXIF data on the photos suggest they were taken on 8th September and I will include it in the official records.

Black-throated Tit is a species which is not doing particularly well in Hong Kong, as this graph of Annual Peak Counts and Number of Locations recorded (from our presentation last week) shows

Kowloon Reservoir catchment is one of the few fairly regular locations, as is Shing Mun. It doesn't seem to be recorded much from Tai Po Kau these days.