Signal Lens
One interesting bit that I noticed about English signals that's different from American signals (aside from literally everything else) is that they had ways that the operator could see the lights from directly beside the signal. On the Underground this was via small lenses on the side of the main ones. On Network Rail, this seemed to be a different bevel in one corner of the lens, allowing it to be seen better from that particular angle.
Signal Lens
One interesting bit that I noticed about English signals that's different from American signals (aside from literally everything else) is that they had ways that the operator could see the lights from directly beside the signal. On the Underground this was via small lenses on the side of the main ones. On Network Rail, this seemed to be a different bevel in one corner of the lens, allowing it to be seen better from that particular angle.