The "office" had a terrace at the back that looked down onto the area now occupied by the Kowloon Commerce Centre and Roxy Industrial Centre - between Tai Lin Pai Road and Kwai Cheong Road. It's the open area with the bus depot on it in the next picture.
The terrace is interesting though because the view from it implies that it may have been part of the old Wader Studio. Sadly I have very little information about the place but it's possible (seeing as Wader was used in another scene) that this terrace was on the Wader back-lot. I don't think anyone will ever be able to answer this for me so I may have to go and find an aerial shot from the same time to confirm.