Yes indeed there are junction indicators/theatre box indicators at junctions, and flashing aspects at certain locations to indicate the highest speed diverging route has been set at a forthcoming junction.
Junction indicators are numbered position 1 - 6 (1 and 2 are shown below) There are some locations where a wrong route can be as insidious as getting position indicator 1 instead of 2.
Theatre boxes will show a letter for a particular line “M” = main, “D” down, or a number for a platform etc.
The key thing is also remembering the last place you can be crossed over for certain destinations (eg the “last chance” crossing locations for Charing +/cannon st kept changing during the London Bridge works).
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