The Class 125 was a design of three car Diesel Multiple Unit built by British Rail in 1958. They were high-density units, externally very similar to the Class 116. They were built specifically for the Lea Valley Line based at Stratford, but were displaced to the ECML suburban lines out of Kings Cross when the Lea Valley Line received over head electrification. Were all withdrawn in 1977 when the ECML suburban lines received 25kV over head electrification, and none survive to this day. Like many first-generation DMU classes, they never carried their 125xxx TOPS set numbers.