Surveillance is often the first thing people picture when they think of a private investigator. A business has concerns about an absence, a solicitor needs to test a party's account of their activities, or a private client wants to understand something that has worried them for months. Observation can sometimes help. It is also one of the most misunderstood investigative services. This guide explains what surveillance involves, what it can and cannot show, and how to approach an investigator so that the work is useful, proportionate and lawful.
Start with the question, not the method
The most useful surveillance briefs begin with a specific factual question. "Find out everything about him" is not a brief. "Establish whether this person attends a particular workplace on weekday mornings during the next fortnight" is.
A clear question does three things. It tells the investigator what to look for, it defines when the work is finished and it lets you judge whether the result has helped. It also makes it easier to see whether surveillance is the right tool at all. Sometimes a company record, a document you already hold or a conversation with a witness will answer the question more directly, with less intrusion and at lower cost. A responsible investigator will say so.
What surveillance can show
Surveillance is planned observation of activity during a defined period. Done well, it can record:
- whether a person attends a particular place, and when
- activity that is relevant to a dispute or a decision
- the dates, times and context of what was seen
- images or recordings, where these can appropriately be obtained
The value lies in an accurate, dated account of what was actually observed.
What it cannot show
Observation records what happened in front of the investigator. It does not reveal what someone was thinking, why a meeting took place or what happened outside the observation period. Seeing two people together does not establish the nature of their relationship. A car outside an address does not, on its own, identify who drove it.
There will often be periods when nothing relevant happens. That is a normal part of the work, not a failure, and it should be reported honestly. A period with no relevant activity does not prove that the activity never occurs. Equally, no investigator can promise that something will be observed, however many hours are booked. Be wary of anyone who guarantees a result.
Privacy and proportionality
Every surveillance request should be assessed for its purpose, necessity and impact on privacy before any work is agreed. Being in a public place does not remove all privacy considerations, and observation can affect other people as well as the person of interest. The Information Commissioner's Office publishes guidance on surveillance and data protection ↗ that is worth reading.
A reputable investigator will decline work that is intended to intimidate, harass or track someone who has chosen not to be in contact. They will also treat vehicle tracking, or anything involving private premises, as a separate matter needing its own assessment, never as an automatic extra. If there is a safety concern or an ongoing legal matter, say so at the start. If a court, tribunal or employment process is involved, your solicitor or HR adviser should help shape the brief.
How to brief an investigator
You do not need a complete file to begin. A short outline covering the following is usually enough for an initial discussion:
- the question you need answered and the decision it will inform
- reliable identifying information you are entitled to share
- relevant locations, dates and any deadlines
- what you already know, where it came from and how certain it is
- your budget and who can authorise changes
Our free guides on surveillance and preparing an investigation brief go into more detail.
How costs are agreed
The cost of surveillance depends on the duration, the number of investigators needed, the locations and travel involved and any expenses. Two jobs described as "surveillance" can need very different resources, which is why a headline price is rarely meaningful.
At PDC, fees are quoted and agreed in writing before any work starts. A sensible approach is often to begin with a short first stage, review what it shows and then decide whether further observation is worthwhile. Ask for a spending limit and a clear point at which you will review progress. Our page on fees, quotations and payments sets out the questions worth asking.
What the report should look like
A good surveillance report is factual and dated. It separates what was directly observed from any interpretation, explains limitations such as lost sight or interruptions, and records periods when nothing relevant happened. It will not settle a dispute on its own, and no investigator can guarantee how findings will be treated in any proceedings.
Talking to PDC
PDC provides surveillance services for private and corporate clients, including in London. You can read more about our approach on our surveillance enquiries page.
If you are considering surveillance and would like a view on whether it is the right step, get in touch. A brief outline of the question is enough to begin, and we will tell you plainly if another approach would serve you better.
Last reviewed: . This article is general information, not legal advice. Laws and official procedures change, so check the original sources before acting.