Due Diligence on a Business Partner: a UK Investigator's Method

Updated 5 October 2026 by Investigation Bureau

Most bad partnerships could have been seen coming. When a partnership, joint venture or investment fails, the warning signs were usually sitting in public records before the contract was signed: directorships nobody mentioned, a string of dissolved companies, litigation the other side kept quiet about. This guide sets out the checks you can run yourself at no cost, and the point at which a professional investigation earns its fee.

Partner due diligence has one uncomfortable rule. The person you are checking has given you their version of events. Due diligence does not mean distrusting people. It means testing whether the version you were given holds up against the record.

The checks you can run yourself today, for free

An hour with public sources answers a surprising amount, before you spend a pound on professionals.

Companies House (free). Every UK directorship your prospective partner holds or has held, and every company they have dissolved, resigned from or seen struck off. It also shows whether accounts and confirmation statements are filed on time. Habitual late filing is a small warning sign, and a fairly reliable one.
The disqualified directors register (free, through Companies House). Whether they have ever been banned from running a company.
The Individual Insolvency Register (free, on GOV.UK). Current bankruptcies, IVAs and debt relief orders.
Court judgments. Registry Trust's TrustOnline service lets you check for CCJs against a person or a company for a few pounds.
Litigation footprint. Search their name and their company names on BAILII and in news archives. People sue and are sued under the names they trade under.
The story itself. Does the career they describe line up with the dates at Companies House? Gaps and overlaps are where the interesting answers are found.

The red flags investigators weigh most heavily

Once the basic record checks are done, an investigator looks for patterns more than single facts.

Phoenixing. A chain of dissolved or struck-off companies in one trade, each new one rising out of the debts of the last.
Directorships they did not mention. Active roles in businesses close to the venture they are proposing to you matter most.
Addresses that do not stand up. A "head office" that turns out to be a virtual-office letterbox does not rule anyone out by itself, but it has to fit the scale of the story you were told.
Ownership that hides. Layers of holding companies or nominee shareholders, where nothing about the business explains the need for them.
A financial history at odds with the lifestyle. Dissolved companies and unsatisfied judgments behind a show of success.

No single item here ends a deal. Each one left unexplained is a question. Several together are an answer.

What professional due diligence adds

A corporate investigation reaches where the free checks cannot.

Verification, not collection. Anyone can print a Companies House record. The value lies in reconciling it with what you were told, one qualification and one date at a time.
Overseas reach. UK registers end at the border. A partner with a history in other jurisdictions needs those countries' registers, litigation records and media checked, in the local language. Cross-border work is handled with trusted partners.
Adverse media and reputation, done properly. Not the first page of a search engine, but archived press, trade sources, sanctions and politically exposed person screening, and discreet human enquiries where they are justified.
Undisclosed conflicts. The competing venture, the family tie to your supplier, the silent partner behind the company you are really contracting with.
A report you can act on. It separates what is evidenced from what is merely alleged, and is written to be shown to your solicitor, your bank or your co-investors.

When to escalate

Our rule of thumb is simple. Escalate when the money at risk is significant, when something in the free checks will not reconcile, or when the other party's history crosses borders. A focused due diligence report costs a fraction of what it protects. We quote it as a fixed price in writing after a scoping conversation, before any work begins. If the public record already answers your question, we will tell you so in that conversation and you keep your money.

Frequently asked questions

Is a background check on a business partner legal in the UK?

Yes. Anyone may lawfully check public registers. Deeper professional due diligence is lawful under UK GDPR on a legitimate interests basis, because a business has a recognised interest in verifying who it contracts and partners with. The tests are proportionality and lawful sources. We are registered with the ICO as a data controller (ZC259849), and we document the lawful basis for every instruction.

Will the person I am checking find out?

Not from us. Register research, open-source work and record analysis cannot be seen by the subject. If a case would benefit from enquiries that might become visible, we tell you first and the decision is yours.

How long does due diligence on a partner take?

The do-it-yourself checks above take an afternoon. A professional UK due diligence report typically takes a few working days, with more time needed for overseas jurisdictions. You get a realistic timeline from us before committing to anything.

How much does it cost?

It is quoted as a fixed project fee after a free scoping conversation. The scope depends on the number of people, companies and countries involved. UK-only checks on one individual and their companies sit at the lower end. Work across several jurisdictions is quoted according to the registers and sources involved. Our guide to what a private investigator costs gives wider context.

What if I have already signed the deal?

Due diligence after signing is still worth doing. It changes how you monitor the relationship, what you put in writing, and how early you act if the pattern proves to be what you feared. If something has already gone wrong, that calls for a fraud investigation, and speed matters.

Check before you sign. Describe the deal to an investigator in confidence. The first conversation is free and carries no obligation, and we will tell you what can be known before you commit: tell us about it in confidence.