London's Ad Experts: The Founder's Vetting Guide

Finding a good Google Ads agency in a place like London feels like trying to find a needle in a haystack, doesn't it? The market is absolutely flooded with agencies all promising the world, using the same jargon, and showing off the same vanity metrics. It's a proper minefield, and if you don't have the expertise to see through the fluff, you can end up burning a lot of cash with very little to show for it. I've seen it happen more times than I can count.

The problem is, most founders start with the wrong question. They ask, "Who is the best agency near me?" when they should be asking, "Who is the best partner to solve my specific growth problem?" The first question gets you a list of local options; the second gets you a shortlist of genuine experts. Let's be brutally honest: your goal isn't to hire a vendor to push buttons in Google Ads. It's to find a strategic partner who understands how to turn ad spend into profitable customers. That requires a completely different vetting process than just checking postcodes and prices.

So, why is your "London agency" search flawed from the start?

Right, let's get this out of the way. The idea that you need an agency you can pop in and have a coffee with is a relic of the past. In today's world, it's one of the least important criteria. I'd take an expert in Manchester who has scaled three of my direct competitors over a mediocre agency in Shoreditch any day of the week. Why? Because results in paid advertising don't come from face-to-face meetings; they come from deep, specific expertise.

Think about it. Does an agency's location in Canary Wharf give them some secret insight into bidding on keywords for B2B SaaS? No. Does being based in Soho make them better at writing ad copy for an e-commerce brand? Of course not. What matters is whether they have walked this path before. Have they managed budgets like yours, for a business like yours, targeting customers like yours? That's the only thing that will move the needle.

We work with clients all over the world from our UK base. The entire process, from initial audit to weekly reporting and strategy calls, is handled remotely. It’s more efficient for everyone. You're not paying for our fancy office rent in our fees, and we're not wasting time on the tube. The focus is 100% on performance. When you're trying to find the right paid ad experts, you need to filter for expertise, not for proximity. It’s a simple mindset shift but it will completely change the quality of the agencies you end up talking to.

What are the real signs of a competent agency?

Okay, so if location is out, what should you be looking for? It boils down to three things: their case studies, the clarity of their communication, and their candour about the realities of paid ads.

First, let's talk about case studies. Don't just glance at the logos. Anyone can slap a well-known brand on their site. You need to go deeper. A good case study isn't a victory lap; it's a strategic breakdown. It should tell you a story:

• -> What was the client's specific problem? (e.g., "CPA was too high at £100, preventing them from scaling.")
• -> What was the hypothesis for the solution? (e.g., "We believed the previous agency was targeting an audience that was too broad and the offer wasn't compelling enough.")
• -> What was the strategy and what did they actually *do*? (e.g., "We restructured the campaigns to focus on high-intent keywords, rewrote the ad copy to focus on the customer's pain point, and A/B tested two different landing page offers.")
• -> What were the measurable results? (e.g., "This reduced the CPA to £7, allowing the client to scale their ad spend by 300% while maintaining profitability.")

See the difference? One is a vague claim, the other is a demonstration of expertise. A great example comes to mind from a campaign we ran for a medical job matching SaaS. They came to us with a cost per acquisition of £100, which was simply not scalable. We brought that down to just £7. The interesting part isn't just the final number, but the strategy behind it—it involved a complete rethink of their targeting across both Meta and Google Ads. That’s the kind of strategic thinking you should be looking for—proof they are thinkers, not just doers.

Next up is clarity, and this is where the initial consultation call is so revealing. This is your number one vetting tool. A bad agency will spend 30 minutes pitching you, showing a generic slide deck, and talking about themselves. A great agency will spend 25 of those minutes asking you sharp questions about your business:

• -> "What's your average customer lifetime value?"
• -> "What are your gross margins?"
• -> "What's your current lead-to-customer conversion rate?"
• -> "What's your sales cycle length?"

They are trying to understand the economic reality of your business so they can figure out if and how paid advertising can actually work for you. If they aren't asking these questions, they're planning to operate in a vacuum, and that's a recipe for disaster. This initial call should feel like a free consultation where you walk away with one or two genuinely useful insights about your own strategy. It's their chance to prove their value, not just ask for your credit card details.

Finally, there's candour. Honesty. The single biggest red flag in this industry is anyone who *guarantees* results. It's impossible. Paid advertising is a dynamic system of auctions, audience behaviour, and creative testing. There are no certainties. A good partner will be upfront about this. They'll talk about benchmarks, potential, and a structured plan for testing and optimisation. They won't promise you a specific ROAS or a number one ranking. They’ll also be honest if they think you're not ready for ads, or if your website or offer needs work first. I've had to tell plenty of potential clients that they'd be wasting their money with us until they fix their landing page conversion issues. It doesn't always win you the business, but it's the right thing to do. If it feels too good to be true, it absolutely is. Finding Google Ads experts who are transparent about this is half the battle won.

Are you even asking the right questions?

When you get on that call, you need to be armed with questions that cut through the sales pitch and get to the heart of their competency. Forget "What's your fee?" for a moment—that comes later. You need to diagnose their expertise first. Here are the questions that actually matter:

1. "Can you walk me through the strategy for a campaign you ran for a client with a similar business model to mine?"
This forces them to move beyond the glossy case study and into the nitty-gritty. Listen for words like 'test', 'hypothesis', 'audience segmentation', 'funnel stages'. If they just say "we targeted these keywords and got this ROAS," it's a surface-level answer. You want to hear the strategic thinking behind the actions.

2. "What's your process for understanding my ideal customer's pain points before you write a single line of ad copy?"
A brilliant answer to this involves customer interviews, review mining, surveying your sales team, and analysing competitor messaging. A lazy answer is "you tell us who to target." Great ads don't talk about your product; they talk about your customer's problems. This question reveals if they understand that.

3. "Beyond clicks and impressions, what are the key metrics you'll use to define success for our campaigns, and why?"
This is a test to see if they think like a business owner or a media buyer. They should be talking about Cost Per Acquisition (CPA), Return on Ad Spend (ROAS), and ideally, connecting those to your Customer Lifetime Value (LTV). If they get excited about Click-Through Rate (CTR), they're focused on the wrong part of the funnel.

4. "Who will be my day-to-day contact, and what's their actual, hands-on experience managing accounts in Google Ads?"
In many larger London agencies, you get sold by the charismatic director, then handed off to a junior account manager with six months of experience. You have every right to know who is actually managing your money and what their track record is. Don't be shy about asking to speak with them directly.

To help you visualise this process, think of it like a funnel. You start wide and systematically narrow down your options based on tangible evidence of expertise.

The maths that actually matters (and why agencies obsessed with CPL are wasting your money)

Now for the most important part. If you take one thing away from this article, let it be this: a low Cost Per Lead (CPL) is often a vanity metric that can lead you down a very expensive garden path. I've seen so many founders get excited because an agency got them leads for £10, only to discover that none of them ever turn into paying customers. A £10 lead that doesn't convert is infinitely more expensive than a £300 lead that becomes a £15,000 customer.

The real question isn't "how cheap can we get leads?" but "how much can we afford to spend to acquire a profitable customer?" The answer to that lies in two acronyms: LTV (Lifetime Value) and CAC (Customer Acquisition Cost). Your LTV is the total profit you'll make from an average customer over the entire time they stay with you. Your CAC is what you spend on marketing and sales to get that customer. A healthy, scalable business typically has an LTV to CAC ratio of at least 3:1. This means for every £1 you spend to acquire a customer, you get at least £3 back in profit over their lifetime.

Let's run through a quick example. Imagine you run a B2B SaaS company in the UK:

• -> Average Revenue Per Account (ARPA): £400 per month
• -> Gross Margin %: 75% (so £300 profit per month)
• -> Monthly Churn Rate: 5% (you lose 5% of your customers each month)

The calculation for LTV is: (ARPA * Gross Margin %) / Monthly Churn Rate.
So, LTV = (£400 * 0.75) / 0.05 = £300 / 0.05 = £6,000.

Each customer is worth £6,000 in profit to your business. With a healthy 3:1 ratio, you can afford to spend up to £2,000 to acquire a single customer (your CAC). Now, let's say your sales team converts 1 in 10 qualified leads into a customer. That means you can afford to pay up to £200 per qualified lead (£2,000 / 10). Suddenly, that £150 CPL from a highly targeted Google Search campaign doesn't look so expensive, does it? It looks like a profitable investment. This is the maths that unlocks scale. Any agency that isn't having this conversation with you is focused on the wrong metrics and isn't equipped to be a true growth partner. A key part of vetting PPC experts is ensuring they focus on ROI, not just clicks.

To make this easier, here's an interactive calculator to help you figure out your own numbers.

In-house vs. Agency in London: a brutally honest cost breakdown

Another question I get asked all the time is whether it's better to hire someone in-house or outsource to an agency. It's a fair question, but founders often miscalculate the true costs involved. They compare an agency's monthly retainer to a single salary and think they've got the full picture. It's not even close.

Let's break down the real cost of hiring a decent, experienced in-house PPC manager in London. You're not looking at a graduate role here; you need someone who knows what they're doing from day one.

• -> Salary: For someone with solid experience, you're easily looking at £50,000 - £70,000 per year.
• -> On-costs: Add about 20-25% on top of that for National Insurance, pension contributions, and any other benefits. That's another £12.5k - £17.5k.
• -> Recruitment Fees: Finding this person will likely cost you 15-20% of their first year's salary. Let's call it £10k.
• -> Software Stack: They'll need tools to do their job properly. A decent keyword research tool, analytics software, landing page builder... that can easily be another £3k-£5k per year.
• -> Training & Development: The paid ads landscape changes constantly. You'll need to pay for courses and conferences to keep their skills sharp.

So, your '£60k hire' is actually costing you closer to £90k in the first year, and you get the expertise of... one person. One person who will get sick, go on holiday, and who might leave in 12 months, sending you right back to square one. There's also the significant cost of their learning curve as they get to grips with your specific business.

Now, compare that to a typical agency retainer, which might be somewhere between £2,000 and £5,000 per month (£24k - £60k per year). For that fee, you don't just get one person. You get access to a whole team: a strategist, a copywriter, a data analyst, and an account manager. You get the benefit of their collective experience working across dozens of different accounts. They've already made the costly mistakes on someone else's dime. They come with their own software stack, established processes, and can hit the ground running much faster. The true cost comparison between agency and in-house is rarely as simple as it seems.

Your final checklist: the actionable vetting plan

Alright, that was a lot of information. Let's boil it all down into a simple, actionable plan you can use to vet your next agency partner. This isn't just about finding someone to manage your ads; it's about finding a partner who can help you grow profitably. Making the right choice here is a proper strategic decision, and one of the most common challanges is simply not knowing where to start when you're not an expert yourself.

Here is the main advice I have for you, broken down into a checklist format. Use this to guide your research, your calls, and your final decision.

Choosing an agency is a big commitment, not just of money, but of time and trust. Getting it right can accelerate your growth in ways you can't imagine. Getting it wrong can set you back six months and tens of thousands of pounds. This framework isn't foolproof, but it will dramatically improve your odds of finding a genuine partner who can deliver real, measurable results for your business.

Ultimately, the right partner will feel less like an outsourced service and more like an extension of your own team. They'll be as invested in your business outcomes as you are. If you'd like to see what that feels like in practice, consider scheduling a free, no-obligation strategy session with us. We'll take a look at your current situation, dive into your numbers, and give you some honest, actionable advice you can use, whether you decide to work with us or not. Hope that helps!