London Underground rolling stock numbering and classification

A number of different numbering and classification schemes have been used for the rolling stock owned by the London Underground and its constituent companies. This page explains the principal systems.

* Abbreviations used on this page for the constituent companies of London Underground include CLR (Central London Railway), LER (London Electric Railway), MDR (Metropolitan District Railway) and Met (Metropolitan Railway).

* For information about individual classes of locomotives and other rolling stock, see: London Underground rolling stock

Electric Multiple Units

The numbering and classification of electric multiple unit stock on the London Underground is usually related to the type of line that the trains are used on. There are two distinct types of line: 'Sub-surface' lines (earlier lines built on the cut-and-cover method, which use trains of similar size to those on the national railway network), and 'Tube' lines (deep-level lines, built to a more restricted size). The 'Sub-surface' lines are the Circle, District, East London, Hammersmith & City and Metropolitan lines; all the other lines are 'Tube' lines.

Unit Classification

The method of classification depends on the type of line the train operates on:

Tube Stock

Tube Stock is classified by the year in which it was anticipated at the time of ordering that it would be delivered (this sometimes proves optimistic), e.g. 1992 Stock.This system was commenced by London Underground with the 1935 Stock. The large number of broadly similar Tube trains built for the LER during 1923-1935 were called 'Standard Stock', although there were many detail differences. They replaced the LER's original 'Gate Stock', introduced for the opening of the Bakerloo, Piccadilly and Hampstead (Northern) lines, and the CLR's 1903 Stock, constructed to replace the locomotive and carriage sets used at its opening in 1900.

ub-surface Stock

Sub-surface Stock is classified by a letter, usually issued sequentially, and which is sometimes followed by the last two digits of the year of delivery, e.g. Q23 Stock.This system was commenced by the MDR for its stock. When the London Underground was formed the ex-Metropolitan Railway units were fitted into this series (types MV, MW, T, V, VT and W). By 1960, most letters had been allocated, and the decision was taken to re-issue 'A' to the new Metropolitan stock. The next sub-surface types were built for the Circle and District lines, and the opportunity was taken to allocate 'C' and 'D' respectively, omitting 'B'.

Types of Unit

On most lines, trains are formed from a pairing or triplet of units. Units are 'single-ended', where there is a driving cab at one end only, or 'double-ended', where there is a driving cab at both ends. In addition, some units have no driving cabs, and thus must always be included in the middle of a formation of units.

Car Classification

The different types of car used to make up electric multiple units are referred to by a series of codes, described below:

Notes:
* 17000 and 20000 were used for cars converted from T Stock in 1946/1947 as prototypes for A Stock. 17000 was renumbered 17001 following further modifications.