Note the map on the left wall, said to be from when Churchill was Lord of the Admiralty. According to the notes for this room, "Some of the most important strategic decisions of the Second World War were taken in this room."
One of the general's offices. The most interesting thing about this room was the green telephone, which was connected to something the size of a suitcase on the floor. It was an early scrambler for voice calls.
Each station was manned by a liaison for a different branch of the armed services. The telephones, called the Beauty Chorus, were direct lines to the the different branches' headquarters all over London.
Note the sugar on the lower left. When the Cabinet War Rooms were unsealed and reopened in the 1970s (for the first time since the war), a packet of sugar was found in this desk. Sugar, being rationed at the time, was highly valuable, and was likely hidden here by one of the last officers to man this desk. 1940s sugar. How cool is that? I wonder how it tastes.
At the entrance of the new World War I area was a really cool display. Projectors mounted on the ceiling, firing down (next slide), project moving images on what look like pieces of paper. A neat effect, done well.