Just discernible on the right had side is a road sign that looks as though it says Nga Tsin Long Road, and a quick look in Streetview reveals it is indeed that road in Kowloon City. The low rise grey building with black trim at the back is the Lee Kee Memorial Dispensary. Leaky or not (ooh, can you see what I did there...:-)), it is still around and looks pretty much unchanged over the past 30 years - save for some additional rooftop railing. Even the paint job is the same. This is at the northern end of the road where it joins onto Carpenter Road. The dispensary was built in 1951 and opened for business in 1952.
It seems that quite a bit of the filming was done in this area so expect more Kowloon City shots over the coming posts.