 Subsequently, some have been fitted with Automatic Train Protection (ATP) equipment, compatible with the system used on the Central line, and some with ATP equipment which enables them to work with the replacement Distance-to-Go Radio (DTG-R) system on the upgraded Victoria line.The first two battery locomotives supplied for the London Underground were manufactured by Hurst Nelson and Co, who were based in Motherwell.They were delivered in August 1905, and were used during the construction of the Great Northern, Piccadilly and Brompton Railway, where they were numbered 1B and 2B.