Introduction The RAF Museum holds what is probably Britain's most comprehensive collection of records relating to companies involved in the manufacture of airframes (i.e. aircraft less their engines) aero‑engines, components and associated equipment. The entries in this guide are arranged by company name and include a history of each company, particularly its formation and that of subsidiaries together with mergers and take‑overs. Brief details of the records, the relevant accession numbers and any limitations on access are given. Where the records have been listed this is indicated. A glossary of terms specific to the subject area is also included, together with an index.