Birmingham Railway Carriage & Wagon (BRCW)
The Birmingham Railway Carriage and Wagon Company (BRC&W) was established in 1854 was a railway locomotive and carriage builder with its premises located at Smethwick, Birmingham.
They built 437 DMU vehicles for British Railways:
The also built two coaches for the LMS in 1925 which later became a DMU - brake thirds 9821 and 9828 became the Davey-Paxman diesel electric test unit.
A book on the company history was released in 1995: "Birmingham Railway Carriage & Wagon Company A Century of Achievement 1855-1963 in Pictures and Words" written by John Hypher, Colin and Stephen Wheeler, but does not have much material specifically on the DMUs.
Online company histories:
Wikipedia
Grace's Guide to British Industrial History
Warwickshire Railways
The surviving company archives are held by Staffordshire County Record Office (also listed in the The National Archives catalogue). They contain some DMU information, such as file D831/4/6/8 "Diesel multiple units, mainly regarding orders for components", a lever arch file containing copies of letters re. the ordering of parts and materials used in the construction of the Class 104s. The file is marked 10/56 – 11/56, and so is only a small glimpse of the whole story, but useful conclusions can be made. Almost all the correspondence relates to the changing of quantities, as there was a change in the differing numbers of individual type of vehicles from first ordered.
Today
Many of the original buildings survive as the the Middlemore Business Park and the Park Rose Industrial Estate (on which the BRC&W star logo can be seen on the Middlemore Road buildings, pictured).
The company name has been resurected by a non-profit organization that plans to secure premises in part of the original works and rebuild some lost locomotive types.