How to Choose a Marketing Agency in the UK (and What to Ask Before You Hire)
Hiring a marketing agency is one of those decisions where the cost of getting it wrong is invisible until it's expensive. A bad agency doesn't just waste the fee — it burns months of ad budget, pollutes your data, and leaves you back at square one having lost half a year. Most small business owners pick an agency on a nice website and a confident sales call. Here's how to choose one properly.
What does a marketing agency actually do?
A marketing agency plans, builds and runs the work that brings you customers — most commonly paid ads (Google, Facebook and Instagram), tracking and measurement, and sometimes SEO, email or content. A good one ties all of it back to leads and sales, not clicks.
The phrase “marketing agency” covers wildly different animals. A brand or creative agency makes you look good — logos, design, campaigns — and usually measures success in awareness. A performance (or digital) agency is judged on numbers: leads, bookings, sales, return on ad spend. For most small businesses spending their own money, you want the second kind. Be clear which you're buying, because the two are easy to confuse on a sales call and very different to live with.
How much should a marketing agency cost — and how should they charge?
Most UK agencies charge either a fixed monthly fee or a percentage of your ad spend (commonly 10–20%). For small businesses, a fixed fee is almost always the safer model: it's predictable, and the agency isn't quietly incentivised to push your budget up.
Think about what each model rewards. A percentage-of-spend agency earns more when you spend more — so “let's increase the budget” is always in their interest, whether or not it's in yours. A fixed-fee agency earns the same regardless, so the only way to keep you is to make the account work. Whichever model you choose, your ad spend should be paid directly to Google or Meta and never marked up, and you should know your total monthly cost before you commit. If an agency won't put a number in writing, that's your answer. (We've broken down real UK figures in how much Google Ads management costs in the UK.)
Who will actually be running my account?
Ask who manages your account day-to-day — by name. At many agencies the senior people who win the pitch hand the actual work to a junior managing dozens of accounts. You want to know who's in your account every week, and whether you can talk to them directly.
This is the single biggest difference between agencies, and it's the one sales decks hide. The person who's brilliant in the pitch is rarely the person who'll be in your account on a wet Tuesday in February. If the honest answer is “an account manager will coordinate with the team,” you're paying senior prices for junior work and a layer of telephone in between. Smaller, founder-run agencies trade scale for the opposite: you deal with the people doing the work. For a small business, that direct line is usually worth more than a big name.
Will I own my ad accounts and data?
Yes — insist on it. Your Google Ads account, Meta account, website tracking and analytics should all be owned by you, with the agency given access. If the agency “owns” them, leaving means losing your history, your data and sometimes your ads entirely.
This catches people out constantly. Some agencies build campaigns inside their accounts so that when you leave, you walk away with nothing — no conversion history, no audiences, no learnings — and your next agency starts from zero. Before you sign, confirm in writing that you own every account and that you keep full admin access. It's your business's data. Treat anyone reluctant to give it to you as a red flag.
How should a good agency measure success?
By the numbers that matter to your business — leads, bookings, sales, cost per lead, return on ad spend — not clicks, impressions or “reach.” A good agency agrees the one or two metrics that mean money for you before they start, then reports against them honestly.
Vanity metrics are where weak agencies hide. Impressions and clicks always go up if you spend more; they tell you nothing about whether the phone rang. Worse, the conversion numbers most agencies report are often wrong — modern tracking quietly loses 20–40% of conversions to iOS and browser restrictions, so the platforms over- or under-count. Ask how they track conversions and whether they've set up server-side tracking. An agency that can't explain how it measures a sale can't honestly tell you whether it's working.
What contract length is normal — and what's a red flag?
Month-to-month, or a short initial term, is the gold standard. Be wary of 12-month lock-ins. A long contract mostly protects the agency — if the work were good, they wouldn't need to trap you in it.
There's a reasonable middle ground: some agencies ask for a 60- or 90-day initial period because tracking setup and the algorithm's learning phase genuinely take that long to show results. That's fair. What isn't fair is an auto-renewing annual contract with a punitive exit. Ask what the notice period is and what happens to your account when you leave. The best answer is simple: “30 days' notice, you keep everything.”
How do I know their results are real?
Ask for specific, recent examples in a business like yours — with real numbers and, ideally, a client you can speak to. Be sceptical of screenshots without context, vague “300% growth” claims, and case studies that never mention spend or profit.
Results are easy to dress up. “We increased conversions by 400%” means nothing if it went from one to five. Ask what the spend was, what a conversion actually was, and whether it made the client money. A confident agency will happily talk specifics or put you in touch with a current client; a nervous one will retreat into jargon. If you're already with an agency and something feels off, here are the signs your agency is underperforming.
The questions to ask before you hire
Take this list to any agency you're considering. The answers — and how comfortably they give them — tell you almost everything.
- Who, by name, will run my account day-to-day? And can I speak to them, not just a salesperson?
- How do you charge — fixed fee or percentage of spend? What's my total monthly cost?
- Do I own my ad accounts and data? Do I keep full access if I leave?
- How will you measure success? Which metric are we judging this on?
- How do you track conversions? Have you set up server-side tracking?
- What's the contract length and notice period?
- Can I see results from a similar business — with real spend figures?
- Who else will touch my account, and do you outsource any of it?
Red flags to walk away from
A few signals reliably predict a bad experience. Any one of these is worth a hard pause.
- Guaranteed results or guaranteed rankings. Nobody can promise positions on Google or a fixed number of leads — the platforms don't work that way.
- They own your accounts. Non-negotiable. Walk away.
- Long lock-in with a painful exit. Confidence doesn't need a 12-month cage.
- Only vanity metrics. If reporting is all impressions and reach, they're hiding the numbers that matter.
- No clear answer on who does the work. Vagueness here means juniors and outsourcing.
- Pressure to decide today. Good agencies have a pipeline; they don't need to rush you.
Big agency or small agency?
For most small businesses, a small specialist agency beats a large generalist one. You get senior attention and a direct line instead of being a small account inside a big roster. The trade-off is that small agencies take on fewer clients — so the good ones have waiting lists.
Big agencies make sense when you need many disciplines at once and have the budget to be a meaningful client. If you're spending £1,000–£100,000 a month and want people who actually know your account, smaller and specialised usually wins. The thing to avoid is the worst of both worlds: a mid-size agency charging big-agency prices while doing junior-level work behind an account manager.
Bons & Frazer is a two-person, founder-run agency. You deal directly with us — fixed fee, no contract, and you own every account. We run Google Ads and Facebook & Instagram ads for small businesses across the UK.
Book a free auditFrequently asked questions
How do I know if a marketing agency is any good?
Look past the website and the pitch. The reliable signals are: they'll name the person running your account and let you speak to them, they charge transparently, they let you own your accounts and data, they measure success by leads or sales rather than clicks, and they'll show you real results from a similar business — with spend figures, not just percentages. An agency comfortable answering all of those plainly is usually a good one. Evasiveness on any of them is the warning sign.
Is it better to pay a fixed fee or a percentage of ad spend?
For most small businesses, a fixed fee. It makes your costs predictable and removes the conflict of interest baked into percentage pricing — where the agency earns more the more you spend, whether or not it's the most profitable move. Percentage models can suit very large advertisers, but for SMEs they tend to quietly push budgets upward. Either way, your ad spend should go straight to Google or Meta and never be marked up by the agency.
How long should a marketing agency contract be?
Month-to-month, or a short 60–90 day initial term at most. A short initial period can be reasonable because tracking setup and the algorithm's learning phase take time to show results. But auto-renewing 12-month lock-ins mainly protect the agency. The best arrangement is a rolling contract with 30 days' notice where you keep all your accounts and data if you leave. If an agency needs a long contract to hold onto you, ask why the work alone wouldn't.
Should a small business use a big agency or a small one?
Usually a small, specialist agency. You get senior people actually working on your account and a direct line to them, rather than being a minor account managed by a junior inside a large roster. Big agencies suit businesses that need many services at once and have the budget to be a significant client. For most SMEs spending £1,000–£100,000 a month, smaller and specialised delivers better attention and better results.
How much does a marketing agency cost in the UK?
It varies by service and scope, but most small businesses should expect management fees from a few hundred to a couple of thousand pounds a month, with ad spend on top and paid directly to the platforms. Beware quotes that seem far below the market — the work is usually being done by a junior or partly automated. We've set out realistic figures in our Google Ads management cost guide.
Do I even need an agency, or can I do it myself?
Plenty of small businesses run their own ads successfully, especially at lower budgets. An agency earns its fee when the time you spend (or waste) is worth more than the fee, when the tracking and account structure are beyond what you want to learn, or when you're spending enough that small improvements pay for the management several times over. If you're below a few hundred pounds a month, doing it yourself or using a short consulting engagement is often the smarter start.
Jamie Frazer is a co-founder of Bons & Frazer, a founder-run performance marketing agency in Norwich specialising in Google Ads, Facebook & Instagram ads and conversion tracking for small businesses across the UK.