A company is a registered company in the UK (mostly private limited companies, plus LLPs, PLCs etc), geocoded I geocoded the company address found on companies house.

Address sharing is huge: about 3.9M of the 6.4M companies share their registered address with at least one other. The record is 71-75 Shelton Street in Covent Garden, with 101,007 companies registered at it. 128 City Road is next with ~53k.

If you click an individual location on the map it should tell you how many companies are at that location.