How to Hire a Private Investigator in the UK

Updated 5 October 2026 by Investigation Bureau

Most people hire an investigator once in a lifetime, and they do it at a moment when they are stressed, suspicious and out of their depth. This guide is what we would tell a friend to check before paying anyone.

Private investigation in the UK is unregulated. Anyone can print business cards tomorrow. Your own ten minutes of checking is the only licensing system there is. This is how to spend them.

Step 1: Be clear about the question, not the method

A good brief is a question. "Is my partner where they say they are on Thursdays?" "Where is the man who owes me £40,000?" "Is my night-shift supervisor doing a second job on my time?" Leave the method to the investigator. It is what you are paying for. Ask for "three days of surveillance" and a poor firm will sell you exactly that, whether or not it is the right tool.

Step 2: Check the basics before the first conversation

A registered UK company you can look up. Search Companies House and confirm the company is active, with named officers. A recent incorporation date is not a warning by itself. A firm that will not give you its registered name and number is. You can check us the same way: Investigation Bureau is a trading name of Bureau Nine Ltd, which is on the register.
An ICO registration and a privacy notice that makes sense. Data protection is not paperwork in this trade. It decides whether the evidence gathered about your subject is lawful and usable. A firm that is casual about it in public will be casual with your case. We are registered with the ICO as a data controller (ZC259849).
A named person accountable for the work. The first reply should come from an investigator who can discuss your situation, not from a sales script. How a firm handles your first contact tells you how it will handle your case.
Independent reviews, read with care. Where a firm has reviews on a site it cannot edit, read the worst first and see how it responded. A young company may have few or none, so lean on the checks that cannot be bought.

Step 3: Ask these five questions in the first conversation

"Is what I want lawful, and will the evidence be usable?" The right answer contains the word "depends", followed by an explanation. Anyone who says "no problem" to everything is a problem.
"Who will actually work my case?" Some firms are lead generators that sell your case on. The investigator you brief should stay responsible for the case and tell you plainly who will be doing the work.
"What will it cost, fixed, in writing?" Our cost guide shows what is normal. Be wary of open-ended hourly billing.
"What do I get at the end?" The answer should be a written, timestamped report prepared to a standard a court can use. "We'll keep you posted" is not an answer.
"What happens if you find nothing?" An honest firm tells you in advance that sometimes nothing is happening, and that a professional negative is a result you can finally rest on.

Step 4: Understand what a professional cannot do

Anyone who offers the following is offering to commit offences, and evidence obtained this way can rebound on you:

Hacking phones, email or social media accounts, or "getting messages back"
Obtaining bank statements, medical records or phone records by deception, known as blagging
Unlawfully tracking a vehicle the client has no rights over (see our GPS tracker law guide)
Harassment, trespass, or using a pretext to trick a subject into incriminating themselves

We refuse all of these. A professional achieves more inside the law than a cowboy does outside it. Lawful surveillance, OSINT, tracing through legitimate data sources and properly preserved digital evidence go a very long way.

Step 5: Brief honestly

The first conversation is confidential. Tell the investigator the whole situation, awkward parts included. Cases go wrong when the client edits the brief: the subject who "doesn't drive" and then leaves in a car, or the "definitely at work on Thursdays" that turns out to mean sometimes. None of it will shock an experienced investigator. It only changes the plan.

Frequently asked questions

Are private investigators legal in the UK?

Yes. Investigation is entirely legal. Particular methods, such as hacking, blagging and harassment, are not. The industry is unregulated, so check a firm's company record, its ICO registration and its grasp of the law. Our guide Is it legal to hire a private investigator in the UK? covers what is lawful, what never is, and where a client can become liable.

How long does an investigation take?

Tracing cases often resolve in days. Surveillance depends on the subject's routine and is typically deployed over 1 to 3 days. Complex fraud or cyber cases can run for weeks. You should always know the planned scope before you pay.

Will anyone find out I hired an investigator?

Not from us. Cases are handled on a need-to-know basis. Communication is arranged around your circumstances, including safe contact times if you share a home with the subject, and the report is delivered in the way you choose.

Ready to talk it through? Every case starts with a free, confidential first conversation and no obligation. Send a confidential enquiry and we reply within one working day.