The episode involves the company being put through their paces on a speedmarch and sees them going through various areas of the New Territories including the place below.
I'll be honest, I was stumped until just today when a nice person on Facebook posted some pictures of the place today. It's called Pak Sha O Ha Yeung and is in Sai Kung near to Hoi Ha Wan. It seems that a nice chappy called Toby took over the place some time in the early 80's when it was almost falling apart and has lovingly restored it to its former glory.
I'll try and get some of my own snaps the next time I am out that way.