Finding a good paid ads agency in London can be a proper headache. You search online and you're hit with hundreds of options, all promising the world. The trouble is, how do you sort the good ones from the ones who'll just burn through your cash? It's not about flashy websites or slick sales pitches. It’s about finding genuine expertise that gets you results. I've been in this game a while, and I've seen what works and what doesn't. This is my no-nonsense guide to help you choose the right partner.
First things first, don't get too hung up on them being right on your doorstep in London. Yeah, it can be nice to meet in person, but for what we do, it's not a deal-breaker. Expertise trumps geography every single time. A top-notch agency in Manchester that knows your industry inside out is going to do a much better job than an average one in Shoreditch that doesn't. Your main goal is to find a team that has proven they can do the job, regardless of their postcode.
So, how do you even start to vet them?
Your first port of call is their website, and the single most important page you should be looking at is their case studies. This is where they should be showing their homework. Don't just skim them. You need to look for a few specific things:
-> Niche Experience: Have they worked with businesses like yours before? If you're a B2B SaaS company, you want to see case studies from other B2B SaaS clients. If you sell courses, look for that. It's not always a deal-breaker if they haven't worked in your *exact* niche, but you want to see that they understand your business model. For instance, we've run lots of campaigns for software companies. I remember one where we got their cost per trial down to $7 on Meta ads, and another where we helped a client get over 4,600 registrations for their B2B software. That kind of specific experience is what you're looking for.
-> Real Results: A case study that just says "we increased traffic" is useless. What does that even mean? You want hard numbers. Look for things like Return On Ad Spend (ROAS), Cost Per Lead (CPL), or Cost Per Acquisition (CPA). For example, for a subscription box client, we hit a 1000% ROAS. For another ecommerce brand selling women's apparel, we acheived a 691% return. Those are the kind of concrete results that show they know what they're doing. If their case studies are all fluff and no substance, that's a big red flag.
-> Platform Knowledge: The case study should give you a clue about which ad platforms they used. If you think LinkedIn is right for your business, you want to see that they have experience there. We recently got a $22 CPL for a B2B software client using LinkedIn Ads, which is a tough platform to crack. That shows we understand the nuances. If all their success is on Meta and you need Google Search, you need to question if they have the right skillset.
After case studies, have a look at their reviews. What are past clients saying? Are the reviews detailed, or just generic "they were great" comments? Look for patterns. If multiple reviews mention great communication and solid results, that's a good sign. But if it all feels a bit thin, you should be cautious.
What should happen on the first call?
Okay, so you've found an agency that looks promising on paper. The next step is to book a call. This is your chance to really test their expertise. A good agency won't just give you a hard sell. They should be trying to understand your business and offer some genuine advice.
We offer a free initial consultation where we actually look at a potential client's ad account and strategy with them. It gives them a real taste of what it's like to work with us. This is what you should be looking for. It shouldn’t just be a discovery call for them to qualify you; it should be a strategy session where you walk away with some actionable ideas, whether you hire them or not. If they're not willing to give you any value upfront, what makes you think they will when you're paying them?
Here are some questions you should definitely be asking:
-> "Based on my business, which ad platforms would you recommend and why?"
Their answer will tell you a lot. A lazy answer is "we'll run ads on Facebook and Google". A good answer is much more thought-out. For example, if you sell high-ticket services to other businesses, they should be talking about Google Search to capture people already looking for a solution, or LinkedIn for its powerful B2B targeting. If you're an ecommerce brand, they should be talking about a mix of Meta Ads for prospecting and retargeting, maybe some PMax and Shopping on Google. Their recommendation should be tailored to *you*.
-> "What's your approach to audience targeting for a business like mine?"
This is where you can see if they have a real methodology. For a platform like Meta, I could talk for hours about audience prioritisation. You start with what you know works. For a new account, that's usually detailed interest targeting. Once you have data, you move to retargeting your website visitors and video viewers (your MoFu/BoFu audiences). Then you build lookalike audiences from your best customers or people who've completed a purchase. They should be able to explain a clear, logical structure like that. If they just say "we'll target people interested in your product," it's too generic.
-> "What kind of results can I realistically expect?"
This is a bit of a trick question. Tbh, in paid advertising, you can't promise anything. Anyone who guarantees you a specific ROAS or CPL from day one is either lying or naive. The market changes, auctions fluctuate, creative fatigues. A good agency will be honest about this. They should be able to give you a ballpark based on their experience with similar clients or industry benchmarks, but they'll also manage your expectations and tell you there will be a testing phase. For example, I might tell a B2C service client that leads on Google could be anywhere from £10-£50, depending on how competitive their area is. We have a home cleaning client getting leads for £5, but an HVAC client in a tough market is paying £60. That's the kind of honest, experience-based answer you want.
Are there any red flags I should look out for?
Absolutely. And they're not always obvious. Here are the main ones I see that should make you think twice.
-> The "Secret Sauce" Pitch: Be very wary of any agency that claims to have a "secret" or "proprietary" method they can't explain. Good paid advertising isn't magic. It's a combination of solid strategy, rigorous testing, good creative, and constant optimisation. They should be able to walk you through their process clearly. If it's all smoke and mirrors, walk away.
-> Long-Term Contracts from Day One: Some agencies will try to lock you into a 6 or 12-month contract straight away. I'm not a fan of this. There should be a trial period, maybe 3 months, to prove they can deliver. If they're confident in their ability to get you results, they shouldn't need to tie you down with a long-term contract before they've even started.
-> Poor Communication: During the sales process, how are they to deal with? Are they quick to respond? Do they answer your questions directly? If they're a pain to deal with before you've even signed, imagine what it'll be like when they have your money. This is a partnership, and communication is everything.
-> The References Issue: This might be a controversial one. If you've seen their detailed case studies, had a deep-dive strategy call with them, and you like their approach, but then you ask to speak to one of their current clients for a reference... for us, that's actually a bit of a red flag. It signals that at the core, you don't really trust us, even after we've shown you everything. That lack of trust can make for a difficult working relationship down the line. A strong portfolio of case studies and reviews should really be enough.
How much is this all going to cost?
This is the million-dollar question, isn't it? The cost breaks down into two parts: your ad spend (the money that goes directly to Google, Meta, etc.) and the agency's management fee.
1. Ad Spend
This is hugely variable. A good starting point for a small business is often around £1,000-£2,000 per month. But a better way to think about it is based on your goals. You need to work backwards. Let's say you want 20 new leads a month, and based on industry benchmarks, a lead might cost you £50. Your minimum ad spend would need to be 20 x £50 = £1,000. Here's a simple table to show what I mean:
| Target Metric | Estimated Cost Per Result | Number of Results Needed | Estimated Monthly Ad Spend |
|---|---|---|---|
| B2C Service Leads (e.g. Electrician) | £10 - £50 | 30 | £300 - £1,500 |
| B2B SaaS Trial Signups | £20 - £80 | 50 | £1,000 - £4,000 |
| eCommerce Purchase | £10 - £75 | 100 | £1,000 - £7,500 |
These are just rough estimates of course. Your actual costs will depend on your industry, targeting, and how good your ads and landing pages are. A good agency should help you set a realistic starting budget and have a plan to scale it as performance improves.
2. Agency Management Fee
This is what you pay the agency for their time, expertise, and work. There are a few common models:
-> Flat Monthly Retainer: This is the most common. You pay a fixed fee each month, regardless of ad spend. It's simple and predictable. This is good for businesses who want a consistent cost each month.
-> Percentage of Ad Spend: The agency takes a cut of what you spend on ads, usually somewhere between 10-20%. This can be good as it aligns the agency's incentives with scaling your spend, but you need to make sure they're scaling profitably and not just spending for the sake of it.
-> Performance-Based: Here, the fee is tied directly to results, like a fee per lead or a percentage of revenue generated. It sounds great in theory because it's low-risk for you, but it's less common. It often requires higher fees to make up for the agency's risk, and can lead to them focusing only on easy, short-term wins rather than long-term brand growth.
There's no single "best" model. It depends on your business and your goals. The most important thing is that the fee structure is transparent and you understand exactly what you're paying for.
How to make your final choice
Choosing an agency is a big decision. You're trusting them with your money and a critical part of your growth. After you've done your research and spoken to a few contenders, you need to pull all the information together. Don't just go with your gut, but do consider who you feel you could build a strong partnership with. It comes down to a blend of proven competence and good chemistry.
I've detailed my main recommendations for you below in a table to help you keep track as you go through the process. Think of it as a checklist to make sure you're not missing anything important.
| Vetting Stage | What to Look For | Key Question to Ask Yourself |
|---|---|---|
| Website Review | Detailed, results-focused case studies relevant to your niche. Clear, professional presentation. Authentic testimonials. | "Do they have hard proof that they can get results for a business like mine?" |
| Initial Call / Consultation | They ask smart questions about your business. They offer genuine, actionable advice. They can explain their strategic approach clearly. | "Did I learn something valuable from this call, or was it just a sales pitch?" |
| Strategy & Proposal | A customised plan, not a cookie-cutter template. Recommends specific platforms and targeting logic. Sets realistic expectations about results and timelines. | "Does this plan feel like it was built specifically for my business and my goals?" |
| Pricing & Contract | Transparent fee structure. No long-term lock-in from the start. A reasonable starting budget proposed for ad spend. | "Do I understand exactly what I'm paying for and what the terms of the agreement are?" |
| Red Flag Check | No unrealistic guarantees. No "secret sauce" nonsense. Good communication and responsiveness. | "Is there anything about this agency that makes me feel uneasy or seems too good to be true?" |
So, do you really need an agency?
You could try to do it all yourself. Some business owners do, and a few are successful. But paid advertising is a full-time job, and it's a specialism. The platforms are constantly changing, and what worked last month might not work today. It's not just about pushing a few buttons in the ads manager.
A good expert or agency brings years of experience to the table. We know the benchmarks, we know what pitfalls to avoid, and we know how to test and optimise efficiently to get your costs down. I've worked on campaigns where we've taken a client's cost per acquisition from over £100 down to just £7. That kind of improvement doesn't happen by accident. It comes from knowing the platform inside out and having a rigorous process.
When you hire an expert, you're not just buying their time; you're buying their experience, their data from hundreds of other campaigns, and their focused attention. You're buying speed. Instead of spending months and thousands of pounds making all the common mistakes, you can get to profitability much faster. For most businesses, the cost of an agency pays for itself many times over in saved ad spend and accelerated growth.
If you're serious about growing your business with paid ads, getting expert help is one of the best investments you can make. It lets you focus on what you do best—running your business—while leaving the complexities of digital advertising to someone who lives and breathes it every single day.
If you've read this and you're thinking you might want some expert help looking at your own strategy, feel free to get in touch. We offer a free, no-obligation consultation to review your current situation and give you some honest advice on how you could improve.
Hope that helps!
