TLDR;
- Finding a good ad consultant in London is hard because most are generalists who talk a good game but can't deliver. You need a specialist who understands your specific business model and customer.
- Forget vetting based on their polished website or sales pitch. The only things that matter are detailed, relevant case studies (ideally in your niche, with results in £) and the quality of advice they give you on a free consultation call.
- The most important question isn't "what will my ROAS be?" but "do they understand my customer's biggest nightmare?". A great consultant focuses on your offer, your customer's pain, and your business maths (LTV:CAC ratio) before they even think about ad creative.
- This guide includes an interactive LTV to CAC calculator to help you figure out exactly how much you can afford to pay for a customer, which is the first step to profitable scaling.
- We'll also walk through a visual flowchart to spot the red flags and green flags during your vetting process, so you don't get stuck with a dud.
I get it. You're based in London, surrounded by thousands of agencies and "growth marketing consultants," and you're struggling to find one that isn't just full of hot air. They all promise the world, show you flashy presentations, and talk about 'synergy' and 'leveraging platforms', but you're left wondering if any of them can actually get you more customers, profitably. The truth is, most of them can't.
The problem is that most founders and marketing managers in London vet consultants the wrong way. They look at the wrong signals and ask the wrong questions. They get sold a dream, sign a 6-month contract, and end up with burnt cash and a metrick-filled report that means absolutely nothing to their bottom line. This guide is here to fix that. I'm going to give you a bulletproof framework for finding and vetting a paid ads consultant in London who can actually move the needle for your business. It's not about finding someone down the road in Shoreditch or Canary Wharf; it's about finding someone with the right, specific expertise.
First things first: Do you even know who you're targeting?
Before you even think about hiring someone to run your ads, you need to have a crystal-clear answer to this question. And I don't mean some vague, demographic-based profile your last marketing intern put together. "Companies in the finance sector in the City of London with 50-200 employees" is a useless starting point. It tells you nothing of value and leads to generic ads that speak to no one. To stop burning cash, you have to define your customer by their pain.
You need to become an expert in their specific, urgent, expensive, career-threatening nightmare. Your Ideal Customer Profile (ICP) isn't a person; it's a problem state. For a legal tech SaaS we worked with, the nightmare wasn't 'needing document management'; it was 'a junior partner missing a critical filing deadline and exposing the firm to a multi-million-pound malpractice suit.' For a B2B software client selling to engineering managers, the nightmare wasn't a clunky workflow; it was the terror of their best three developers handing in their notice out of sheer frustration, putting a critical product launch in jeopardy.
Once you've isolated that nightmare, you can find them. Where do they hang out online? What niche podcasts do they listen to on their commute on the Tube, like 'Acquired'? What industry newsletters do they actually open every morning, like 'Stratechery'? Are they members of the 'SaaS Growth Hacks' Facebook group? Do they follow people like Jason Lemkin on Twitter?
This intelligence is the blueprint for your entire advertising strategy. Any consultant worth their salt will force this conversation with you. If a potential consultant jumps straight into talking about platforms, audiences, and ad formats without first digging deep into this 'nightmare scenario,' they're a tactician, not a strategist. That's your first major red flag. Do this work first, or you have no business spending a single pound on ads, whether you do it yourself or hire a B2B ads consultant in London.
Do you know your numbers? The maths that actually matters
The second conversation a great consultant will have with you is about your business economics. Most founders are obsessed with the wrong metrics. They ask, "What CPL (Cost Per Lead) can you get me?" or "What ROAS (Return On Ad Spend) can I expect?" These are secondary questions.
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 lies in its counterpart: Lifetime Value (LTV). If you don't know this number, you are flying blind. A good consultant will help you figure this out, but you should have a rough idea yourself.
Here's the simple maths:
Average Revenue Per Account (ARPA): What do you make per customer, per month? Let's say it's £500.
Gross Margin %: What's your profit margin on that revenue? Let's say it's 80%.
Monthly Churn Rate: What percentage of customers do you lose each month? Let's say it's 4%.
The calculation is straightforward:
LTV = (ARPA * Gross Margin %) / Monthly Churn Rate
LTV = (£500 * 0.80) / 0.04
LTV = £400 / 0.04 = £10,000
In this example, each customer is worth £10,000 in gross margin to your business over their lifetime. This number changes everything. With a £10,000 LTV, a healthy 3:1 LTV:CAC (Customer Acquisition Cost) ratio means you can afford to spend up to £3,333 to acquire a single customer. If your sales process converts 1 in 10 qualified leads into a customer, you can afford to pay up to £333 per qualified lead.
Suddenly, that £250 lead from a CTO on LinkedIn doesn't seem expensive, does it? It looks like a bargain. This is the maths that unlocks aggressive, intelligent growth and frees you from the tyranny of chasing cheap, low-quality leads. A consultant who doesn't frame their strategy around your LTV:CAC ratio is just gambling with your money.
Interactive LTV & Affordable CAC Calculator
How to actually vet a consultant (and not get ripped off)
Okay, so you know your customer's nightmare and you know your numbers. Now you're ready to start talking to people. This is where the real vetting begins. Forget their fancy office address or their slick sales deck. Here’s what you need to scrutinise.
1. Case Studies are everything.
This is your number one piece of evidence. But don't just glance at them. You need to dissect them.
-> Are they recent? Results from 2019 are irrelevant in today's market.
-> Are they detailed? A good case study walks you through the problem, the strategy, the execution, and the specific results. It shouldn't just be a logo with "10x ROAS" slapped next to it.
-> Are the results in pounds (£)? If you're a UK business, you want a consultant who understands the UK market. Seeing results in dollars might mean their experience is primarily US-based, which can be a very different advertising environment.
-> Most importantly, are they relevant to YOU? If you're a B2B SaaS company, a case study about a Shopify ecommerce store selling womens apparel is almost useless. You need to see proof they've solved a similar problem for a similar business. For instance, in one campaign for a medical job matching SaaS, we brought their cost per acquisition down from £100 to just £7, and for another B2B SaaS client, we generated 1,535 trials. That's the level of specific, relevant proof you should be looking for.
2. The "Free Consultation" is your battlefield.
Every consultant and agency offers a "free consultation" or "strategy session." This is not a sales call for them; this is your chance to test their expertise for free. Your goal is to walk away with at least one genuinely actionable insight you could implement yourself tomorrow.
-> Do they ask probing questions? A great consultant will spend 80% of the call asking about your business, your customers, your offer, and your numbers. A bad one will spend 80% of the call talking about themselves and their 'process'.
-> Do they give you real advice? Don't let them get away with vague statements. If they say "we need to improve your creative," ask them "Okay, based on my website, what's the first creative angle you would test and why?". If they say "your targeting could be better," ask "Who is the first lookalike audience you would build and from what source event?". Push for specifics.
-> To be honest, if someone asks for references after we've already shared detailed results from past campaigns and provided a free, in-depth account review, it can be a red flag. It suggests a lack of trust that can hinder a successful partnership. The proof of expertise should be evident in the specific results they can show you and the quality of the live advice they provide.
3. Location doesn't matter, expertise does.
You're looking for a consultant "in London". Why? Is it so you can meet them for a coffee in Covent Garden? That's a nice to have, not a need to have. The best consultant for your B2B software company might be in Manchester, Edinburgh, or even working remotely from another country. What matters is their specific, niche expertise. Don't limit your search geographically. That said, a UK-based consultant will inherently understand the cultural nuances and market costs better than one based overseas. But I'd take a specialist in another UK city over a generalist in London every single day. There are many different ways to figure out the right approach, from doing it all yourself to choosing between a consultant, agency, or in-house team.
Spotting the Charlatan: A Vetting Flowchart
To make it even clearer, let's visualise the vetting process. When you're on that initial call, mentally run through this checklist. Where does the consultant you're talking to land?
They're selling you, not solving for you.
They're trying to understand the problem.
Tactician, not a strategist. Likely cause of ads not converting in London.
This person understands growth levers.
Your offer is probably the real problem
I'm going to be brutally honest. Most of the time when a founder comes to us saying "my ads aren't working," the ads aren't the real problem. The problem is the offer. A great consultant will tell you this, even if it's not what you want to hear. A bad consultant will take your money and try to slap some lipstick on a pig.
The "Request a Demo" button is one of the most arrogant Calls to Action in B2B marketing. It presumes your prospect, a busy decision-maker, has nothing better to do than book a 30-minute slot in their diary to be sold to. It is high-friction, low-value, and instantly positions you as just another commodity vendor. If this is your main call to action, your ads will struggle, I guarantee it.
Your offer’s only job is to deliver a moment of undeniable value—an "aha!" moment that makes the prospect sell themselves on your solution. For SaaS founders, the gold standard is a free trial (no credit card required) or a freemium plan. Let them use the actual product. Let them feel the transformation. When the product itself proves its value, the sale becomes a formality. We've seen this work time and time again for our SaaS clients, generating thousands of trials that convert to paying customers.
If you're a service business, you must bottle your expertise into an asset that provides instant value. For a marketing agency, this could be a free, automated SEO audit that shows them their top 3 keyword opportunities. For us, as a B2B advertising consultancy, it's this exact kind of in-depth guide or a 20-minute strategy session where we audit failing ad campaigns for free. You must solve a small, real problem for free to earn the right to solve their bigger problems for a fee. If a consultant isn't challenging your offer and pushing you to make it more valuable and lower-friction, they're not doing their job.
What should you expect to pay in the UK?
This is a common question, and the answer is... it depends. But I can give you some realistic benchmarks based on the campaigns we've run for UK and international clients. The key drivers are your industry, your target audience, and the conversion goal.
As you can see, the costs vary wildly. For an ecommerce store selling cleaning products, we might see a Cost Per Purchase of £10-£30. For a home cleaning service, we've seen CPLs as low as £5. But for a B2B software targeting CTOs in the finance industry on LinkedIn, a CPL of £70-£150 for a qualified lead would be considered a great result. I remember one client in environmental controls where we reduced their CPL by 84% on LinkedIn, but it was still a significant investment per lead because the contract values were huge. The absolute cost is less important than the cost relative to your LTV. This is why knowing your numbers is the foundation of any successful ad campaign.
This is my advice on how to hire the right ad consultant for your London business:
I've detailed my main recommendations for you below. This is the process you should follow. It's not a quick fix; it requires you to do your homework. But it will save you thousands of pounds and months of frustration in the long run. If you're serious about growth, this is the work you need to do.
| Vetting Step | What to Look For (Green Flags ✅) | What to Avoid (Red Flags 🚩) |
|---|---|---|
| 1. Internal Prep | You have a clear definition of your customer's "nightmare problem." You've used the calculator to get a solid grasp of your LTV and affordable CAC. | You have a vague idea of your target audience and no clue about your unit economics. You're hoping the consultant will figure it all out for you. |
| 2. Case Study Review | Detailed walkthroughs of campaigns for businesses like yours. Clear problem, strategy, and results shown in £. Recent and relevant. | Vague results ("10x returns!"), irrelevant industries, outdated examples, or just a page of client logos with no context. |
| 3. The Consultation Call | They ask more questions than you do. They focus on your offer, funnel, and business maths. They provide at least one specific, actionable idea you can use. | They talk about their "proprietary process," promise specific results (e.g., "we guarantee a 5x ROAS"), and avoid getting into the details of your business. |
| 4. The Proposal | The strategy section is customised to your business, referencing points from your call. It outlines a clear testing plan and defines what success looks like (based on your CAC goals). | A generic, copy-paste document that could have been sent to any business. Focuses on deliverables (e.g., "4 new ad creatives per month") instead of outcomes. |
| 5. The Decision | You feel confident they understand your business on a strategic level and have a logical plan to test their way to success. You feel like you're hiring a partner. | You feel like you've been "sold" to. You're excited by the big promises but have a nagging feeling they didn't quite 'get' your business. |
Why you might need an expert after all
You could take all this advice and try to implement it yourself. For some businesses, that's the right move, especially at the very beginning. But running paid advertising campaigns effectively is a full-time job that requires deep specialisation. The platforms change constantly, and what worked six months ago is often obsolete today.
The difference between an amateur and a professional isn't just about knowing which buttons to press. It's about the speed of learning. An expert has managed millions in ad spend across dozens of accounts. They've already made the costly mistakes, seen what works and what doesn't across different industries, and can apply those learnings to your account from day one. They can get you to profitability faster and help you avoid burning through your budget on failed experiments.
Choosing the right partner is one of the most important decisions you'll make for your company's growth. It's not just about finding a pair of hands; it's about finding a strategic brain that can help you navigate the complexities of customer acquisition. When you find the right fit, it's not a cost; it's an investment that pays for itself many times over.
If you're a founder or marketing lead in London (or anywhere else in the UK) and you're serious about scaling your business with paid advertising, the next step is to put this guide into action. Start vetting. If you'd like to see how we stack up against this very framework, we offer a free, no-obligation 20-minute strategy session. We'll dive into your business, your numbers, and your goals, and you'll walk away with actionable advice you can use immediately, whether you decide to work with us or not.
