Remains of a stone wall and possible foundation on the hill above the barbeque site, on the bush path up to PB 401. Pictures from the Industrial History of HK site show various buildings constructed around that area; it may be related to one of those as the stonework seems to have more in common with waterworks than military.
Up the first flight of stairs on the Maclehose trail going towards Shing Mun Redoubt. At the first flat path section there will be one or two large 'cuttings' into the earth, below the trail. Directly below about 10-15 Meters is the larger, accessible tunnel. This one had lots of bush and vines going into the portal, and had obviously had not been entered in quite a while. The tunnel is of standard width-height of the smaller ones and had a split. Both splits get much more narrow until inaccessible, but still go on. The total length of tunnel accessible is around 30-35 meters.
Lieutenant Wayabiyashi was the officer who led the opening attack on The Shing Mun Redoubt, and effectively led to its fall. He was able to utilize the cover of darkness on the early morning of the 10th of December to skirt around the pillboxes of the Shing Mun Redoubt and go over the reservoir dam, attacking the redoubt from the rear. He led the group of 20 highly motivated men of the 229th IJA Infantry Regiment, and according to memoirs, they used only grenades and blades in capturing the redoubt.
G. B. Gifford Hull was Resident Engineer on the Jubilee (Shing Mung) Reservoir. His name is inscribed on the memorial stone at the Reservoir which was begun in 1933 and finished in 1937.
http://en.wikipedia.org/wiki/File:HK_ShingMumReservoir_MemorialStone.JPG
