The UK has the single best open company register of any major market, it is free, it has an API, and most people prospecting the UK have never opened it. That is the headline.
This is one of a set of country guides. The overview of how to read any directory is here, and the others are the USA, Australia, Canada and the UAE.
The layers, ranked
| Source | Type | Contact details | Freshness | Best for |
|---|---|---|---|---|
| Companies House | Official register | Registered office only | Very high | Qualification, age, status, directors |
| Live map data | Listing | Phone, website, hours | Very high | Local and service businesses |
| Yell | Legacy listing site | Phone, website | Medium to high | Broad coverage across trades |
| Trade accreditation schemes | Vetted member list | Phone, website | High | Trades, home services, contractors |
| Chambers of commerce | Member list | Phone, website | High | Local B2B in a specific region |
| Trade associations | Member list | Often a named person | High | B2B into a defined industry |
| Review platforms | Review site | Phone, website | High | Businesses where trust is the sale |
| Credit reference products | Commercial data | Varies | High | Financial qualification at scale |
1. Companies House
Every limited company and LLP in the UK must file, so the register is complete for incorporated businesses and correct by legal obligation rather than by goodwill. It is free to search, and there is a public REST API and bulk data products for structured access.
What it gives you that nothing else does:
- Company age. Incorporation date, exactly.
- Status. Active, dormant, in liquidation, dissolved. This alone will save you from a chunk of wasted outreach.
- Directors and officers. Names, appointment dates, and other directorships, which is how you spot groups and multi-site operators.
- Filing history and accounts. Small companies file abbreviated accounts, so exact turnover is often absent, but account type and filing pattern are a usable size proxy.
- SIC codes. Industry classification, useful for segmenting, and worth treating with suspicion because plenty of companies pick one at incorporation and never revisit it.
What it does not give you: a trading email address or phone number. The registered office is very often the accountant, so do not treat it as a mailing address.
Use it as: the qualification layer over a contact list you built elsewhere. Sourcing from the register and then hunting for contacts is the slow direction; sourcing contacts and then enriching from the register is the fast one.
2. Live map data
For anything with a physical location or a service area, this is the most current business data in the country, and again the reason is incentive: the business maintains the listing because customers use it to find them.
Name, category, address, phone, website, hours. Enough to identify the business and judge its size, and the website gets you to a real inbox. This is what live discovery reads from, rather than a stored database, because a database is a photograph and a live query is a look out of the window.
3. Yell
The descendant of the Yellow Pages and still the broadest general listing site in the UK. Coverage is wide, freshness is medium: businesses that pay for a listing keep it current, and the free entries drift.
Best for: breadth across trades, and for reaching long-established businesses whose web presence is thin.
4. Trade accreditation schemes
This is the UK's genuine advantage and the layer most worth your attention.
Britain runs an unusual number of vetted-trade schemes: Checkatrade, TrustMark, Gas Safe Register, NICEIC, FMB, Which? Trusted Traders and a long tail of trade-specific bodies. A business listed on one has paid money and passed a check.
Two consequences for prospecting. The list is pre-qualified, since the business already demonstrated it invests in credibility. And the listings carry real contact details, because the entire point is that customers can reach them.
Best for: anyone selling to trades, contractors and home-services businesses, which is a large share of UK small business.
5. Chambers of commerce
Accredited chambers cover most regions and publish member directories. Members are businesses that pay for local visibility, which is the same qualification filter as everywhere else.
Best for: local B2B, particularly professional services selling within one region.
6. Trade associations
Whatever your target market does, there is a body for it, and its member list is smaller and better than any database you could buy. It also gives you an opening line built on shared context rather than "I came across your website".
Start from the trade rather than from a list of associations. The body will be obvious once you know what the business calls itself.
7. Review platforms
Current, and they carry the signal a register cannot: what customers complain about. A business whose recent reviews mention the same operational failure twice has written your first line for you.
What about paid UK databases?
The commercial products built on top of Companies House add credit scores, financial ratios, group structures and, sometimes, contact data. For financial qualification at scale that is genuinely valuable and hard to replicate.
For contact data, be clear about what you are buying: a scrape of the free sources, taken at some point in the past, resold widely. The addresses that went stale are the ones that will bounce, and a high bounce rate is one of the fastest ways to have your mail filtered for everybody. Bounce rates and what normal looks like.
The legal part, and it matters more here
The UK line is not "B2B is fine". PECR distinguishes corporate subscribers from individual subscribers, and that is a different cut than most people assume.
- Corporate subscribers (limited companies, LLPs, public bodies) may be sent unsolicited marketing email without prior consent, provided you identify yourself, do not disguise the sender, and give a working way to opt out.
- Individual subscribers, which includes sole traders and most partnerships, are treated as individuals. They require consent or another lawful basis, even where the address looks entirely commercial.
That distinction bites in exactly the market most people prospect: a large share of UK trades are sole traders. A list of plumbers from an accreditation scheme is not uniformly a corporate-subscriber list, and Companies House is precisely the tool that tells you which is which.
UK GDPR applies on top, to the personal data inside a named business address, with its own transparency and objection obligations. Our PECR guide goes deeper and the GDPR guide covers the wider EU position. None of it is legal advice.
Putting it together
- Segment. Trade, region, one size signal.
- Harvest contacts from live map data, a trade accreditation scheme, or a chamber list.
- Enrich from Companies House for status, age, and crucially entity type, which decides what you may lawfully send.
- Verify every address. Non-negotiable.
- Write something specific. Then follow up four or five times.
Leads Ranger runs steps 2 to 5 in one workflow, from live discovery through verification to sequences sent from your own mailboxes, with replies landing in one inbox on a built-in CRM. The browser extension handles the directories themselves: on any listing page in Chrome, Firefox or Edge, it takes the businesses on screen into your pipeline, deduplicated on arrival.