What are whistle boards?

Whistle boards are signs placed at the side of railways tracks to inform train drivers of when they should blow their whistle (or horn) to warn the public and railway workers of an approaching train.

Originally, the signs had the full word 'WHISTLE' printed across them but this was revised in the mid-1960s to show just a black letter 'W' on a white background. Since then, there has been a few trials and experiments with the signs including, an 'SW' sign on the Western Region that means 'Sound Horn', a double-whistle sign (one W above another) which indicates that both tones of a two-tone horn are to be used, a silhouette of the letter W that isn't affected by graffiti or snow and a whistle sign with a cross printed above meaning a continuous blast of the whistle or horn is required over a predetermined distance.

Although there are many variations of the whistle board used in real life, the most common versions found on model railways are the 'WHISTLE' type and the simpler black 'W' on a white background.