Description
The LMS, LNER and SR introduced flanged upper quadrant signal arms around 1936. They were used for all new installations (on tubular steel posts and dolls, or rail-built posts and lattice dolls on the SR), and to replace lower quadrant arms on signals inherited from the relevant pre-Group companies. BR adopted the design, and new semaphore signals are still being installed today, where replacement by colour lights is inappropriate.
