At HKG, the Left Luggage operation is on the Arrivals level at the far left as you enter the airport from the Express Train or street facing "in" towards the gates. It is a paid storage area, not an unattended locker. I have found them very helpful and honest. I once left my Nikon on the counter and walked away with my luggage. When I realized it and returned about 30 minutes later, not only were they holding my camera at their desk, but they had noted my name (from the info on the records of the luggage I had just retrieved) after I walked away; and they requested photo identification before releasing the camera to me. I was pleased and impressed with the service.