British Diesels & Electrics is a railway blog which will aim to cover every single class of locomotive and multiple unit which has run on British rails, including metro systems and street railways.

The vast majority of photography is by myself, some photos have been purchased and scanned for new extinct classes of locomotive and unit I did not manage to see in the past (and probably wouldn't be able to ever unless they invent a time machine). See the footer of this blog for copyright information.

Total Operations Processing System (TOPS)

TOPS which is a computer system adopted by British Railways in the 1960s to help keep tabs on, organise and control its fleet of rolling stock. Under TOPS every class of locomotive and multiple unit was given a unique class number and running number derived from it.

For example the BR DJ15 class of shunter was renamed the Class 03 and individual locomotives numbered 03 001, 03 002 and so on.

The following is a list of the number bands allocated to the various types of locomotive and multiple unit operated by British Railways (and successors) since the mid-1960s. TOPS has been modified over the years, and there are a number of areas of overlap especially where a number band has been exhausted.

Diesel Locomotives (01-79)

01-13 Diesel Shunters
14-20 Type 1 (1000hp or less)
21-31 Type 2 (1001-1499hp)
32-39 Type 3 (1500-1999hp)
40-54 (and 57) Type 4 (2000-2999hp)
55-79 Type 5 (3000hp plus)

Electric Locomotives (70-96)

70-79 DC powered and electro-diesel
80-96 AC powered

Diesel Multiple Units (100-299, 600-699)

100-199 Diesel mechanical
200-299 Diesel electric
600-699 New DMU allocation, as yet not used

Electric Multiple Units (300-899)*

300-399 AC powered (original allocation)
400-499 DC powered (Southern Region)
500-599 Other DC powered
700-799 AC/DC powered (new allocation)
800-899 New high speed units

* Bi-mode units (e.g. AC and DC powered) tended to be listed under the 3xx range

There are also numbers allocated to departmental vehicles and other special vehicles in the 9xxs.
From the Class 03 shunter 03 073