As built the 24 straight electrics classified as Class 71 under the TOPS scheme were initially numbered in the E5000 series between E5000 and E5023. However before the implementation of the TOPS renumbering scheme 10 of the Class had been rebuilt into electro-diesels and renumbered into the E6101 to E6110 number range, later to become Class 74, and some renumbering between those remaining within the E5000 series took place to fill in the gaps left by those converted.

Initially E5000 was renumbered to E5024 at the end of the series to do away with having a Class member with a number ending in 000, a Southern Region thing, but this locomotive was eventually, along with E5003 E5005 E5006 E5015 E5016 E5017 E5019 E5021 and E5023, selected for conversion to a Class 74 and renumbered into the E61XX series.