London's Guide To Vetting PPC Experts (That Deliver ROI)

Finding a good PPC expert in London can feel like trying to find a needle in a haystack, and frankly, it's bloody difficult. The city is crawling with agencies, from one-man-bands working out of a flat in Hackney to huge firms with shiny offices in Canary Wharf. They all promise the world—guaranteed results, massive ROI, streams of new customers. But the truth is, most of them are just sales machines who are great at pitching and not much else.

The real challenge isn't just finding someone to run your ads. It's finding a partner who actually takes the time to understand your bussiness, your customers, and what you're trying to achieve. It's about finding someone who speaks in terms of profit and lifetime value, not just clicks and impressions. So, let's cut through the noise. This isn't about finding the cheapest agency; it's about finding the one that will make you the most money. And that starts with knowing what to look for and what questions to ask.

So, what should I be looking for first? Case studies, right?

Yes, but you need to know how to read them. Any agency can cherry-pick their best result and slap a massive "1000% ROAS!" headline on it. Tbh, that number is often meaningless without context. When you're looking at case studies, you need to dig a bit deeper. You're not looking for a sales pitch; you're looking for evidence of a repeatable process.

First, look for niche relevance. Have they worked with businesses like yours? If you're a B2B SaaS startup in the Old Street tech roundabout, a case study about a local plumbing company is pretty much useless to you. You need to see that they understand the nuances of your industry. For example, we've worked with a lot of B2B software companies, and we know that getting a trial signup on Meta for $7 is a solid result, whereas a lead on LinkedIn for $22 is also great because the lead quality is often much higher. That's the kind of specific experience you should be looking for.

Next, what was the actual business problem they were hired to fix? A good case study won't just say "we increased traffic." It'll say something like, "the client was struggling to scale their ad spend past £10k a month without their Cost Per Acquisition sky-rocketing." I remember one client, a medical job matching SaaS, came to us with a CPA of around £100. It was crippling their growth. We managed to reduce that to just £7. That's a story about solving a real, painful business problem, not just tweaking a few keywords.

Finally, do they explain *how* they did it? Look for details on their methodology. Did they restructure the Google Ads account? Did they focus on creative testing on Facebook? Did they use specific targeting on LinkedIn? If the case study is just fluff and big numbers with no substance, it's a red flag. They should be able to walk you through the strategy. This shows they have a proper process and aren't just getting lucky. A good agency's case studies will give you a real taste of their expertise before you even pick up the phone. If you want to know more, we've got a detailed guide on how to properly vet ad experts in the UK.

How do I know if they can actually get me a return on my investment?

This is the most important question, and the answer has very little to do with what the agency charges. The real answer lies in your own business metrics. Too many founders get obsessed with vanity metrics like cost-per-click (CPC) or click-through-rate (CTR). Who cares if you're paying £0.50 a click if none of those clicks ever turn into paying customers? The real question isn't "How low can my CPL go?" but "How high a CPL can I afford to acquire a truly great customer?"

To figure that out, you need to know your Customer Lifetime Value (LTV). A good agency will ask you about this. A bad one won't even mention it. If you don't know your LTV, you're flying blind. It's the key to understanding how much you can profitably spend to acquire a customer (your Customer Acquisition Cost, or CAC).

Here's the basic maths:

LTV = (Average Revenue Per Customer Per Month * Gross Margin %) / Monthly Churn Rate

Let's say you run a SaaS business. Your average customer pays you £300 a month, your gross margin is 80%, and you lose 5% of your customers each month. Your LTV would be (£300 * 0.80) / 0.05 = £4,800. A healthy LTV:CAC ratio is generally considered to be 3:1. This means you can afford to spend up to £1,600 to acquire a single new customer. Suddenly, paying £150 for a qualified lead from Google Ads doesn't seem so expensive, does it?

I've built a little calculator here so you can play around with your own numbers. This is the kind of thinking that separates profitable advertising from just burning cash.

An expert who understands this will build a strategy around acquiring high-value customers profitably, not just chasing cheap leads that never convert. They will help you understand the true ROI of your campaigns. If you're looking for more info on this, our founder's guide to London agency pricing and ROI is a good read.

What questions should I ask them on the first call?

The first call is your chance to really vet their expertise. Forget the sales pitch you've heard a dozen times. Your job is to get past that and see if they actually know what they're talking about. This is where you can separate the real experts from the pretenders.

Don't just ask about their pricing structure. Instead, try these questions:

• "Based on my business and goals, which advertising platforms would you prioritise and why?" This tests their strategic thinking. A good answer won't just be "Google and Facebook." It'll be specific. For example, "For your high-ticket B2B service, I'd start with LinkedIn Ads to target specific job titles and company sizes, combined with a Google Search campaign targeting people actively looking for a solution. Facebook might not be the best place to start as the targeting isn't as precise for your needs."


• "Can you walk me through a campaign you ran for a similar business? What were the biggest challenges you faced?" This gets them talking about real-world experience. The "challenges" part is important. Anyone can talk about their wins. An expert will be honest about the difficulties and how they overcame them. It shows they've actually been in the trenches.


• "How do you approach testing and optimisation? What's your process?" You're looking for a structured answer here. A great response would be something like: "We'd start by split-testing two different audience types and three different creative concepts. After a week, we'd analyze the data, turn off the worst performers, and reallocate budget to the winners. Then we'd introduce new variations to constantly try and beat our control." A vague answer like "we monitor the campaigns and make adjustments" is a massive red flag.


• "What data and access would you need from me to get started?" This simple question shows if they're data-driven. They should be asking for access to your Google Analytics, ad accounts, and information about your customer LTV and sales conversion rates. If they don't seem interested in your data, they're probably planning to just guess.

On the flip side, there are some huge red flags to watch for. The biggest one is anyone who guarantees results. It's impossible to guarantee a specific ROAS or number of leads in paid advertising. Anyone who does is either lying or inexperienced. Also, be wary of pushy sales tactics or an over-reliance on jargon. A true expert can explain complex ideas in simple terms.

To make it easier, here's a simple flowchart of how a good vetting process should look.

Should I hire a big London agency or a smaller specialist?

This is a question that stumps a lot of founders. You see the big agency names with their impressive client logos and assume they must be the best. But that's not always the case, especially for small to medium-sized businesses.

A big London agency certainly has its advantages. They have more resources, a wider range of services (SEO, content, PR, etc.), and often a lot of manpower. However, there are significant downsides. The senior experts you meet in the sales process are rarely the people who will actually work on your account. More often than not, your business will be handed off to a junior account manager with maybe a year's experience. You become a small fish in a very large pond, and your account doesn't get the strategic attention it needs. Their processes can be slow and bureaucratic, and their high overheads (think expensive offices near Bank station) are passed directly on to you in their fees.

On the other hand, a smaller, specialist or 'boutique' agency offers a very different experience. Their main advantage is deep expertise in a specific area. You might find an agency that *only* works with B2B SaaS companies, or one that specialises exclusively in high-end eCommerce. This means they already understand your market, your customers, and what strategies actually work. You'll almost certainly be working directly with the senior experts and founders of the agency, the people whose reputation is on the line. They're more agile, can make decisions faster, and tend to be more invested in your success because your results directly impact their business.

In my experience, for most startups and SMEs, a specialist agency is almost always the better choice for generating real ROI. They provide the senior-level expertise you're actually paying for. While a big agency might look impressive on paper, a specialist partner is more likely to feel like an extension of your own team. There's a lot to consider when weighing up an agency versus hiring in-house, but for external help, specialism often wins.

What sort of performance can I realistically expect in the UK market?

It's important to have realistic expectations from the start. The London and wider UK market is highly competitive, which means advertising costs can be higher than in other regions. Anyone promising you page one rankings on Google overnight or leads for pennies is not being straight with you.

The cost per result depends hugely on your industry, your target audience, and your conversion goal. Getting someone to sign up for a free newsletter is obviously going to be much cheaper than getting them to purchase a £2,000 product.

However, I can give you some rough ballpark figures based on our experience running campaigns in developed, English-speaking countries like the UK. For a simple conversion like a lead or a signup, you could expect a Cost Per Click (CPC) somewhere between £0.50 and £1.50. With a decent landing page converting at 10-30%, your Cost Per Acquisition (CPA) would land somewhere between £1.60 and £15.00.

For eCommerce sales, the numbers are different. Landing page conversion rates are naturally lower, usually in the 2-5% range. This means your cost per purchase could be anywhere from £10 to £75, or even higher for expensive items. A good agency will focus on improving your Return on Ad Spend (ROAS) rather than just the cost per sale. For one of our eCommerce clients selling women's apparel, we managed a 691% return, which was a fantastic result for them.

Here’s a simple chart to visualise these ranges.

Remember, these are just averages. A skilled expert can often beat these benchmarks by a significant margin through better targeting, compelling creative, and landing page optimisation. The goal is to start with a realistic baseline and work methodically to improve from there. This might mean starting with a small test budget to gather data before scaling up what works. For many businesses, grappling with the reasons for a low ad ROI in London comes down to not having found their ideal customer yet.

Okay, I think I've found someone. What happens next?

Once you've done your due diligence and chosen an agency or consultant, the real work begins. A good partnership is collaborative. It's not a "set and forget" service where you hand over your money and hope for the best. You should expect clear and regular communication.

The onboarding process should be thorough. They should want to learn everything about your business: your sales cycle, your best customers, your profit margins, and your past marketing efforts. The more they know, the better they can tailor their campaigns. If they just want your credit card details and nothing else, that's a bad sign.

Expect regular reporting, but make sure it focuses on the metrics that actually matter to your business. A report full of impressions, clicks, and CTRs is mostly noise. You want to see leads, cost per lead, sales, and return on ad spend. The reports should clearly show what's working, what isn't, and what the plan is for the next period. It should be a tool for making business decisions, not just a document that gets filed away.

Finally, a good partnership is built on trust. Tbh, we find that if a potential client has reviewed our detailed case studies, had a free strategy session with us where we've audited their account, and *still* asks for references to speak to our other clients, it's an instant red flag for us. It signals a fundamental lack of trust that will likely cause problems down the line. You need to feel confident that you've hired an expert and then let them do their job. Micromanaging your agency will only stifle their ability to get you the best results.

Finding the right expert is a process, but putting in the effort upfront will save you a huge amount of time, money, and headaches in the long run. I've detailed my main recommendations for you below:

Ultimately, the right PPC expert can be one of the best investments you make in your business's growth. The wrong one can be a costly mistake. By taking a structured, evidence-based approach to your search, you drastically improve your chances of finding a true partner who can help you scale profitably.

If you're currently running ads and you're not happy with the return, or if you're thinking about getting started, it can be helpful to get a second opinion. We offer a free, no-obligation 20-minute strategy session where we'll take a look at your ad campaigns and give you some actionable advice. It's a good way to get a taste of the expertise you should expect from any potential partner.