We use this term on ths site to refer to a commercial entity, whether family run or not, operating over a certain period of time. The tendency was to keep the name of its founder or a later representative whenever it acquired a status or reputation worth perpetuating, in the form “X and Co.(mpany)” or “X and Sons”).
In some cases the continuity of such a firm might be retrospectively doctored and its origin reinvented, in keeping with an advertising principle already well-understood in the period concerned.
Certain suppliers, traders etc. appearing in the Guide do not mention the name of the firm or company on their storefront, commercial documents, marks, etc. The “Firm” category is in many cases more effective than the “Business” category in identifying the relevant “marks”.