London's Ultimate Guide To Vetting Paid Ad Experts

I hear this all the time. You're based in London, you need more leads, and you're trying to find someone who can run paid ads without just burning through your cash. The problem is, the London market is absolutely saturated with agencies that talk a great game but deliver very little. They show you glossy reports full of clicks and impressions, but the phone isn't ringing and your sales pipeline is empty. It's frustrating, and it makes you think paid advertising just doesn't work for your business.

Tbh, the problem isn't the advertising; it's the approach. Most agencies are just button-pushers. They set up a campaign, let it run, and hope for the best. They don't dig into the fundamentals of your business, and that's why they fail. Finding a reliable service that delivers a positive ROI requires a completely different way of vetting them. You need to stop buying a service and start looking for a strategic partner who understands how to build a predictable engine for growth.

So, why do most London agencies get it wrong?

It's simple really. They're incentivised to do the wrong things. Their business model often relies on signing you up to a long retainer, doing the minimum amount of work to keep you happy for a few months, and then replacing you when you eventually leave. They focus on what's easy to measure and report on, not what actually drives your business forward.

You'll see them brag about "brand awareness" or "reach." Let me be brutally honest: for most B2B service businesses, "brand awareness" is a trap. You are paying the world's most sophisticated advertising platforms to find people who are the *least* likely to ever buy from you. Why? Because their attention is cheap. The algorithm is just doing what it was told: find the most impressions for the lowest cost. The best form of brand awareness is a happy customer, and that only comes from getting actual leads that turn into sales. Everything else is a distraction.

Another issue is that London is one of the most competitive markets on the planet. Whether you're a tech startup in Shoreditch or a financial consultancy near Canary Wharf, you're fighting for the attention of a very busy, very skeptical audience. A generic approach that might work elsewhere just won't cut it here. You need a partner who understands the nuance of the local market and isn't just applying a cookie-cutter template they use for all their clients. This is why a deep understanding of your specific customer is non-negotiable.

What should I be looking for instead?

You need to shift your mindset. You're not hiring someone to "run ads." You're hiring a strategist to solve a business problem: a lack of qualified, profitable leads. Their job starts long before they ever log into Google Ads or LinkedIn. A good expert will be obsessed with three things: your customer, your numbers, and your offer.

Their process shouldn't start with "what keywords should we target?" It should start with "who is your absolute ideal customer, and what is the expensive, urgent, career-threatening nightmare that keeps them awake at night?" If an agency can't answer that, or worse, doesn't even ask, they are not the right fit. They need to understand the pain before they can sell the solution.

Here’s a rough look at how a proper expert's process compares to a typical agency's. It's less about the specific steps and more about the philosophy behind it: one is focused on activity, the other is focused on outcomes.

How do I define my customer's 'nightmare' for an agency?

This is the most important work you can do, with or without an agency. Forget demographics like "companies with 50-200 employees". That tells you nothing. You need to get specific about the *problem state* your ideal customer is in. Your customer isn't a job title; they're a person with a problem that is causing them real pain.

Let's take an example. Say you're a London-based IT consultancy.

• -> Bad ICP: "We target CTOs at mid-sized tech firms in London." (Useless)
• -> Good ICP: "Our ideal customer is a Head of Engineering at a Series B FinTech startup. She's terrified of a security breach that could get them fined by the FCA and destroy their reputation before their next funding round. She's frustrated because her best engineers are spending all their time patching legacy systems instead of building the new features their investors are demanding."

See the difference? The second one gives an agency everything they need. They know the pain points (security risk, wasted developer time), the emotional drivers (fear, frustration), and the business context (FCA fines, funding rounds). From this, they can craft ad copy that speaks directly to that Head of Engineering. The ad stops being about "IT services" and becomes about "securing your next funding round by eliminating compliance risks." It's a completely different conversation.

This is the level of detail you need to provide, and any agency worth their fee should be pulling this information out of you during the discovery process. If they don't, it's a massive red flag. Many business owners find that if their London ads are not converting, the root cause is often a mismatch between their ads and a deep understanding of their customer's real problems.

Okay, so what does a good lead gen strategy actually cost in London?

This is the "how long is a piece of string" question, but we can put some realistic boundaries on it. For most B2B services in a competitive market like London, you'll primarily be looking at Google Ads (for people actively searching for a solution) and LinkedIn Ads (for targeting specific job titles and industries).

Based on our experience running campaigns for B2B clients, a qualified lead from LinkedIn can cost anywhere from £20 to £200+. I remember one B2B software client we worked with saw a CPL of around $22 (£18) on LinkedIn, which is fantastic, but that's not always typical. For highly specific, senior decision-makers, it can be much higher. On Google Ads, a click could be £5-£15, and if your landing page converts at 5%, that's a CPL of £100-£300. We ran a campaign for an environmental controls company where we managed to reduce their CPL by 84%, but it started high.

The key isn't to find the cheapest leads. It's to find leads that are profitable. And that brings us to the most important calculation you're probably not doing.

You can use this simple calculator to get a rough idea of what your starting ad spend budget might need to be. This is just for the ads themselves, not agency fees, which we'll get to later.

How do I know what I can afford to pay for a lead?

This is where we seperate the amateurs from the pros. 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?" The answer is your Customer Lifetime Value (LTV). If you don't know this number, you are flying blind.

Any agency you consider hiring should make this one of their first questions. If they don't, they are planning to manage your budget based on guesswork. The calculation is simple, but it's the most powerful number in your business.

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

Let's say you run a SaaS company. Your average customer pays you £1,000/month, your gross margin is 80%, and you lose 3% of your customers each month.
LTV = (£1,000 * 0.8) / 0.03 = £800 / 0.03 = £26,667

Suddenly, paying £200 for a lead doesn't seem so expensive, does it? If you close 1 in 10 of those leads, your Customer Acquisition Cost (CAC) is £2,000. Your LTV:CAC ratio is over 13:1, which is incredibly healthy (a good target is 3:1 or higher). This is the maths that unlocks aggressive, intelligent scaling and is the absolute core of a successful framework for achieving ROI on your London ad spend.

Here's a calculator to work out your own LTV. Play around with the numbers and see how small changes in churn or pricing can dramatically change what you can afford to spend on ads.

What killer questions should I ask a potential agency?

Once you're on a call with a potential agency, you need to cut through their sales pitch and get to the core of their competence. Forget asking about their "process." Instead, ask questions that force them to demonstrate their strategic thinking. Answering these correctly is a core part of a good vetting framework for any London B2B business.

Here are a few of my favourites:

1. "Based on what you know about my business, what would be your target Cost Per Acquisition, and how did you arrive at that number?" - This tests if they're thinking about LTV and your business metrics, or just pulling a number out of thin air.
2. "Walk me through a campaign you ran for a UK-based client that failed initially. What went wrong, and what did you do to fix it?" - Everyone has campaigns that fail. Honesty here is a good sign. It also shows their problem-solving ability. If they claim they've never had a campaign fail, they're lying.
3. "Can you show me a case study for a B2B service business similar to mine? Not just the results, but the strategic thinking behind it." - You need to see proof that they have relevant experience. Look for the 'why' behind their actions, not just the 'what'.
4. "Beyond running the ads, how would you suggest we improve our offer or landing page to increase conversions?" - This shows if they are a strategic partner or just a "media buyer." A good expert cares about the entire funnel, because they know a brilliant ad campaign pointed at a bad website is a waste of money.
5. "What's your communication and reporting style? I'm not interested in vanity metrics like impressions." - This sets the expectation from day one. You want reporting focused on leads, cost per lead, sales, and ROI. Not fluff.

Their answers to these questions will tell you far more than any slick presentation. For a more comprehensive checklist, you might want to review a full guide on how to properly vet paid ads experts in London before you sign any contracts.

How do I spot the red flags before it's too late?

There are a few classic warning signs that should have you running for the hills. Spotting these early will save you a lot of money and headaches down the line. It's also worth looking into what typical London ad agency fees are so you know if you're being quoted something that's way off the mark.

So, what's the final step in choosing the right partner?

After all the research and calls, the final test is the free consultation or strategy review. This is where the rubber meets the road. Tbh, we offer this to potential clients and it's often the deciding factor. It's a chance for them to get a taste of our expertise, and for us to see if we're a good fit.

A good strategy session is NOT a sales pitch. They should come prepared, having already looked at your website and your market. They should provide you with actual, actionable advice that you could go and implement yourself. They might point out major flaws in your website's call to action, suggest a completely new angle for your ad messaging, or identify a new audience you'd never considered. You should leave the call feeling like you've learned something valuable, whether you hire them or not.

If the "strategy session" is just them asking you questions they should already know the answer to and then showing you a generic slide deck about their services, it's a waste of time. Their willingness to provide value upfront is the single biggest indicator of what it will be like to work with them. This entire process, from start to finish, is really a playbook for ensuring your success with paid advertising in London.

I've detailed my main recommendations for you below as a final checklist to follow. Stick to this, and you'll dramatically increase your chances of finding a partner who can actually deliver a return on your investment.

Is it worth getting expert help?

Look, you could definately try to learn and do all of this yourself. But as a founder or business owner in London, your time is your most valuable asset. The learning curve for paid advertising is steep, and mistakes are expensive. A small error in targeting or a poorly worded ad can waste thousands of pounds very quickly.

Working with a real expert isn't an expense; it's an investment in a system for predictable growth. They bring years of experience from running hundreds of campaigns, they know what works and what doesn't, and they can get you results far faster than you could on your own. It frees you up to focus on what you do best: running your business, talking to customers, and closing the leads that the campaigns generate.

If you're tired of guessing and want a clear, data-driven approach to generating leads in London, it might be time to talk to someone who does this day in, and day out. If you'd like, we offer a completely free, no-obligation 20-minute strategy session where we can take a look at your business and give you some actionable advice. It's the same process we've used to help clients like a medical job matching SaaS reduce their CPA by over 90% and others generate six-figure revenues. Feel free to get in touch if you think that would be helpful.