War Department Marker

I'm familiar with the British Army's use of stone pillars bearing the letters "W" and "D" separated by an arrow pointing upwards to denote the boundary of War Department land (https://gwulo.com/hong-kong-war-department-boundary-stones), but I hadn't seen this sort of marker before. It's situated on the side of Cape Collinson Road, about 50 meters higher up and on the opposite side to the Hong Kong Buddhist Cemetery building. A plastic pipe, partly concrete clad, leads uphill from the marker.

Given the inscription, the obvious conclusion is that it marked the position of a British Army telephone cable, but I find this a bit surprising due to the increased risk of damage or tapping that openly advertising it would bring.