A signaller is a person who gives signals or directions to others, usually in situations like train or military operations, to help coordinate and guide their actions. Full definition
Designed by William H Hamlyn, the principal architect of the London Midland & Scottish Railway, it was opened in 1938 and was the first residential rail training centre in the UK, capable of housing up to 50 railway operatives and signallers at a time. (qaeducation.co.uk)
Life as a railway signaller turns out to be more monkish than life as a monk, especially on night shifts. (premierchristianity.com)
They are full of virtue signallers who want the public that they are the compassionate ones, and yet here it is for all to see that there is nothing more vicious and Stalinist than the left scorned. (labour-uncut.co.uk)