Details of extant records on Archives Network Wales for the following;

• Evan Jones & Son, Caernarfon, records 1869-1957 
  "The firm (Evan Jones a'i Fab) was an ironmongers, motor engineers and cycle agent, based in Caernarfon. Evan Jones also had business premises at Ebeneser and Penygroes, Caernarfonshire..."
• Griffith Jones, Solicitor, Caernarfon, papers 1822-1947
  "The firm was primarily concerned with conveyancing, mortgages and leases, dealing with properties in Caernarfonshire and Anglesey...."
• Poole, solicitors, of Caernarfon, papers 1521-1936
  "The firm of Messrs Poole, solicitors, was based in Caernarfon.It was established by Richard Poole (fl. 1771-1812) of Beaumaris, Anglesey......."

• 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.