Audience research
Part of Before you commission marketing agencies audience research
Marketing agencies buyer personas work best when built from client data
How marketing agencies build buyer personas that survive internal scrutiny, with interview sizes, a costed example in pounds and UK data sources.
What to take away
- A buyer persona earns its place only if it changes a decision, such as who you pitch to or where spend goes next.
- Build each profile from interviews plus at least one public dataset, so a sceptical colleague can check the basis.
- Segment on budget authority and buying behaviour rather than job title alone.
- Cost the work before you start. A six-interview project with desk research can land near £1,300 as an illustrative internal estimate, not a market rate.
- Refresh every two quarters, because device habits and client priorities move.
Start with the decision, not the demographic
Most persona documents fail because they describe a person instead of supporting a choice. Name the decision first. Is it which sectors to target, which proof to lead with, or where the next £5,000 of spend goes?
Name the decision first
Which sectors should we target?
Persona supports sector choice
Cut the attribute
Put that decision at the top of the document. Every attribute you add afterwards has to help answer it, otherwise cut it.
If you are starting from scratch, the wider audience research guide for England explains how personas sit alongside other research.
Collect evidence before you write a profile
Primary interviews remain the strongest input. Six to ten conversations per segment is usually enough to hear the same objections repeat. Ask what the buyer had to justify internally and what nearly stopped the purchase.
Evidence inputs before writing
- 6-10interviews per segment
- ONSinternet access baseline
- Repeatsame objections heard
Public data fills gaps that interviews cannot cover, particularly channel reach. The ONS bulletin on internet access reports household and individual internet and device access across Great Britain, which is the baseline for any claim about reaching an audience online.
Segment on buying behaviour, not job titles
Two marketing managers at similar companies can behave nothing alike. One holds the budget and signs. The other researches and recommends. Treat them as separate personas, because your approach to each differs.
Useful dividers are budget authority, procurement involvement and in-house capability. Job title is a label: handy for finding people, weak for predicting behaviour.
Behavioural segments also survive the reshuffles that client-side marketing teams go through.
A worked example with labelled costs
Suppose a ten-person agency in Leeds wants personas for its B2B content offer. Six interviews with past enquirers, with a £50 voucher each, cost £300, and transcription is £90.
Two days of desk research at an internal rate of £350 a day adds £700, while a three-hour workshop with two staff, each costed at £40 an hour, adds £240. Total internal cost: £1,330, an illustrative planning figure rather than a quoted market price.
If you want to test those findings against a wider sample, a paid survey platform is often cheaper than more interviews, and our guide to marketing agencies survey tools in England sets out what the main options charge.
Write profiles your team will actually use
Keep each persona to one page: the decision, the evidence, then three or four instructions for the sales team.
Use the buyer's own phrasing, because that wording feeds straight into messaging. Skip invented hobbies and fictional names: they add length and give colleagues an excuse to dismiss the document.
Give each persona a working label, such as the in-house lead who must justify spend to a finance director.
Where generative AI fits, and where it does not
AI is good at summarising interview notes, grouping objections and drafting a first version of a profile. It cannot supply the evidence. The IPA guidance on using generative AI in advertising covers the legal questions, including copyright and disclosure.
Label anything drafted with AI and check every claim against a source. Where a persona uses client quotes, confirm consent before circulating it.
Health, safety and consent during fieldwork
Research often means travel to client offices or workshops on site. Employers must assess and manage those risks, and the Health and Safety Executive sets out the framework employers follow.
Store interview notes under your data protection policy, and tell participants how their words will be used.
Common questions
How many interviews does one persona need?
Six to ten per segment is a workable starting point for a small agency. Stop once new conversations stop producing new objections.
Do personas need names and photographs?
No. Behavioural labels are easier to defend and keep the focus on decisions. Invented names encourage colleagues to treat a profile as fiction.
How often should buyer personas be refreshed?
Every two quarters in fast-moving sectors, and after structural changes such as new procurement thresholds.
Can a persona be built without interviews?
Partly. Public data describes reach and channel behaviour, but not what a buyer must justify internally. Expect a thinner profile.
