Companies House: the company register
Companies House holds the register of every UK limited company: accounts, filings, directors, charges, and registered office. Search and documents are free on the public website, and a free API key unlocks programmatic access for developers.
Use it to vet suppliers, check who you are dealing with, and research competitors' size bands from filed accounts.
Business statistics from the ONS and DBT
The Department for Business and Trade publishes annual business population estimates; London had around 1.04 million private sector businesses in 2025, the most of any UK region. The ONS publishes counts of VAT/PAYE-registered businesses by industry and geography.
These official counts are the right citations for a business plan — far better than blog-repeat figures with no source.
London-specific open data
The London Datastore, run by the Greater London Authority, publishes economic, transport, and demographic datasets for the capital, including borough-level business counts.
Contract awards from public bodies appear on Contracts Finder and Find a Tender — useful both for suppliers hunting work and for anyone researching market prices.
Quick checklist
- Companies House register bookmarked
- DBT business population estimates for planning citations
- ONS UK business statistics for industry counts
- London Datastore for borough-level data
- Contracts Finder / Find a Tender for public procurement