 Following the introduction of the 1929/30 batch of Standard Stock, which was the first to be fitted with electro-pneumatic brakes, a decision was taken to convert all of the Standard Stock to use this system.Most had been fitted with the new equipment by 1936, but the exceptions were the motor cars running with the 1920 stock.These were not converted until 1938 when the 1920 stock was withdrawn from passenger service.