Many thanks for this clarification. Two nations divided by a common language, as they say!Correct. Nothing to do with signalling as we understand it. Arms vertically upwards is the norm, no orders. If at 45 degrees it is "slow, collect orders from a hoop [both loco and conductor in caboose] and read them as you continue". Horizontal is "Stop here for orders". The actual signals guarding the crossing are a bit further back and unconnected with this, some can be seen in the second photograph. In typical US railroad division of duties, Orders are given out by a Operator from the station, the signals by a Towerman from the adjacent Tower (signalbox).