Cefn Du Manuscripts 1878-1928 - details of extant records on Archives Network Wales
"Until 1928 the Cefn Du Slate Quarry, situated in the parishes of Llanrug and Llanbeblig, was one of the most important of the minor quarries of Caernarvonshire...."

• TNA provide:
  • A very useful  Research Guide: Companies and business
  • Their National Register of Archives (NRA) ("Discovery") is particularly useful for finding the location of the archived records of named organisations
• The Association of Business Historians creates and disseminates knowledge about business history.
• TNA hold some railway company records. (Ancestry provides subscription access to the TNA's railway employment records 1833-1958, from a number of historic railway companies.)
• Some employers' and trade association archives are held by Warwick University's Modern Record Centre.
• Trade directories can provide some information (including advertisements) about businesses, large and small, through the years.
• Railway Work, Life and Death - records of railway worker accidents in Britain between 1911 and 1915 - "a joint initiative between the University of Portsmouth and the National Railway Museum (NRM)".
• The John Lewis Memory Store: ". . . a living history of John Lewis & Partners. Through the site, people share their memories, photos, maps and information about John Lewis & Partners, past and present."
• United Kingdom Cemetery Records, from Interment.net.