The Prince and the pitboards
Following my piece on pit-signals (August) I reread Prince Chula’s book Wheels at Speed. He explains the signals were “a round black disc with a white number for number of laps run, a square black board with white number for Bira’s position in race; above a line the number of the car in font of him, below it, by how much. The go-faster sign was a yellow disc with, in red, the first letter of the Siamese word for ‘fast’, to ‘come in’ a blue disc with a red Siamese first letter was used, for ‘stop’ a red disc with yellow Siamese letter.”
Chula explained that using Siamese was not to keep signals secret but to make them sufficiently different for Bira to “recognize them in a flash”.