ARP portal 052 [????- ]

Found this photo on the Getty Archives dated 23 December 1941:

http://www.gettyimages.com/detail/79665688/Popperfoto

Nice find!

Yes, it looks like number 52. Though I think their caption for the photo is wrong:

World War II, 23rd December 1941, Hong Kong, Asia, The entrance to a tunnel air-raid shelter, drilled into a solid rock hill, The British Crown Colony has already been bombed by Japanese warplanes flying across from Kowloon

You would need more than an umbrella for protection in that part of town on 23rd Dec! And if you look at this photo taken shortly after the surrender (so probably 26-31 Dec), you can see the portals' numbers had been painted on by the time fighting began:

Also the Getty photo still shows some construction hoarding next to the entrance, which is gone in the later Harrison Forman photo (the one with the pillbox) shown above.

So the Getty photo was likely taken earlier in the year, shortly after the tunnel was finished.