Is It Legal to Hire a Private Investigator in the UK?

Updated 5 October 2026 by Investigation Bureau

Yes. Anyone in the UK, a private person or a business, may lawfully hire a private investigator. The law is not interested in the hiring. It is interested in the methods. A professional investigator stays inside the law from start to finish, and a careless one can leave you liable for what was done in your name.

People ask this almost as early as they ask about price. This guide sets out the whole position: what an investigator may lawfully do for you, what no one may do at any price, and how the courts treat what is found.

What can a private investigator legally do in the UK?

A good deal, and it is effective work:

Surveillance in public places. Watching, following and filming someone in public is lawful where it serves a legitimate purpose, is proportionate to that purpose and stops short of harassment.
Open-source intelligence (OSINT). Research into information that is publicly available: social media, court records, Companies House, the land registry, the press and the open web.
People tracing. Finding someone through licensed data sources, with the personal data processed under UK GDPR on a documented lawful basis. That basis is usually legitimate interests, for example recovering a debt or reuniting a family.
Discreet enquiries. Talking to people who may know something, without deceiving them about anything material.
Preserving evidence. Timestamped video, notes made at the time and chain-of-custody handling, so that what is found can be used.

One fact surprises most people: private investigation in the UK is unregulated. Nobody needs a licence to trade as an investigator. The government announced a licensing scheme in 2013 and never brought it in. So checking who you hire matters a great deal. Our hiring guide sets out the checks, which take about ten minutes.

What is illegal, even for a private investigator?

Paying for any of the following does not make it lawful. Whoever offers them is offering to commit a criminal offence:

Hacking a phone, an email account or a social media account. This is an offence under the Computer Misuse Act 1990.
Blagging. Getting bank statements, phone records or medical records by deception is a criminal offence under section 170 of the Data Protection Act 2018.
Intercepting phone calls, messages or post.
Harassing the person under investigation, contrary to the Protection from Harassment Act 1997.
Posing as a police officer, contrary to the Police Act 1996.
Unlawful vehicle tracking. A GPS tracker is lawful or unlawful depending on who fits it, to which vehicle and on what basis. Our GPS tracker law guide explains the detail. It is why tracking belongs in a professional service where the lawful basis is settled first.

Here is the point people overlook: if you instruct unlawful methods, the liability reaches you as the client. Ask someone to hack an account or blag records and you can be prosecuted for conspiracy alongside them. The "evidence" would be worthless in any case.

Is evidence from a private investigator admissible in court?

Evidence that was gathered lawfully generally is. Family courts, employment tribunals and civil courts in the UK routinely accept professional surveillance footage, tracing reports and an investigator's testimony, and judges take account of how the material was obtained. Material obtained unlawfully can be excluded. It can bring down a case that was otherwise strong, and it can give the other side a counter-claim. That is the practical argument for hiring people who treat legality as a working discipline and not as a line in an advert.

How do data protection rules apply?

A professional investigation company handles personal data as a data controller in its own right. That means registering with the ICO, recording a lawful basis for each case, collecting no more than the case needs and keeping what it holds secure. We are registered with the ICO as a data controller (ZC259849), which you can confirm on the ICO's public register, and we run every case file to that standard. If a firm cannot tell you its lawful basis in plain English, that tells you something.

How to make sure the investigator you hire works lawfully

Put the question directly: "Is what I want lawful, and will the evidence be usable?" A credible answer usually begins with "it depends".
Confirm there is something real behind the name: a registered UK company you can look up at Companies House, and a named person who is accountable for the work.
Look the company up on the ICO's public register.
Have the scope, the price and the deliverable fixed in writing before any work begins.
Notice what they refuse. A firm that never says no to an unlawful request is a risk to you.

Frequently asked questions

Can a private investigator access bank accounts, phone records or medical records?

No. No private investigator has a lawful route to these without the account holder's consent or a court order. Anyone who says otherwise is proposing a crime, and evidence obtained that way can come back on the client who paid for it.

Do private investigators need a licence in the UK?

No. The industry is unregulated, so anybody may call themselves an investigator. In effect your own checks stand in for the licence: the company record, the ICO registration, a named person who answers for the work, and whether they can talk sensibly about the law from the first conversation.

Can I get in trouble for hiring a private investigator?

Not for the hiring, which is entirely legal. You become liable only if you instruct unlawful methods or knowingly benefit from them. Brief a professional honestly and let them design the lawful route. The risk then sits with the method, in the hands of people who know the law.

Is it legal to have someone followed in the UK?

Yes, provided it is proportionate, serves a legitimate purpose (doubt about a marriage, workplace fraud, tracing a debtor) and keeps to public places. Carried out obsessively or intrusively, it can become harassment. That is why professionals plan surveillance around a specific evidential objective.

Ask us directly. Put your situation to an investigator and we will tell you plainly what is lawful and what it would achieve. Send a confidential enquiry and we reply within one working day.