The highest cross at the top is indeed what would have been the then Palace Court Hotel — a magnificent Art Deco style building, still standing and operating as a hotel under a different name.
The second cross down is indeed the Gaumont cinema; currently the Odeon and under threat of closure; in fact, judging by the period of this shot, it was probably still called the Regent, and had not that long been built: it looks as if this is pre the 1943 air-raid. You can just make out the sort of 'cupola' on the top of the theatre's magnificent dome (visible level with and just to the left of the X)
The third, lower cross does indeed indicate the upper floors of the premises just at the start of Westover Road as it leaves Gervis Place. At one time, Austin Reed occupied part of this end of the building, however, I'm not sure if it would have been at the time of this photo. It is possible this might have been where Fuller's was — although one poster above said it was further along near the Gaumont, my own memory of it was more up this end, so if Fuller's is significant, perhaps that's what the cross was there for? I remember there was a rather tiny tea-room on the ground floor, and a slightly more spacious one on the first floor; my Gran used to take me there for tea and cakes, and I'd clamour to go upstairs, as there was a lovely view over the gardens; but she never wanted to climb the stairs, because of her bunions!