I think this is a Richard's Pipit.
The choice is between Richard's and Upland - there are most unlikely to be any Olive-backed Pipits in Hong Kong in June, they do not stay here for the summer.
Richard's is more buff coloured (yellowish) and Upland more rufous (reddish) - see the following photo which I know is Upland
However, the best way to tell between them is by call.
Upland makes a loud whistle starting with a long
weeeeeeeeeeeee and ending with a brief
tch. This call can be hear from a long distance and is the best way to find Upland Pipits on Tai Mo Shan.
Richards makes a short harsh
schreep when it flies off.
