London's Ad Expert Guide: Vetting For Growth

Finding a decent paid advertising consultant in London can feel like a proper nightmare. The city is flooded with agencies and freelancers all promising the world, but very few actually deliver measurable results. The real risk isn't just burning through your ad budget; it's the massive opportunity cost of picking the wrong partner while your competitors are scaling.

The problem is that most founders don't know how to properly vet them. They get sold on slick presentations and vague promises, only to end up with a hefty invoice and a report full of meaningless metrics like 'impressions' and 'reach'. This guide is designed to give you a framework to cut through that noise. It's about asking the right questions, understanding your own numbers, and identifying a partner who genuinely understands how to drive growth, not just run ads.

Why do most London founders hire the wrong ad consultant?

Honestly, it usually comes down to a few common mistakes. The London market is incredibly competitive and expensive, so these mistakes get amplified fast. You can't afford to get it wrong here.

The biggest trap is focusing on the wrong things. Founders get fixated on low management fees instead of the value and expertise being offered. A cheap consultant who wastes £5,000 of your ad spend is a lot more expensive than a top-tier expert who turns that same £5,000 into £25,000 of revenue. It's about ROI, not cost.

Another classic error is being swayed by guarantees. If anyone ever tells you they can "guarantee results," you should run. I'm serious. We've run hundreds of campaigns for everyone from SaaS startups in Shoreditch to eCommerce brands, and the one constant is that you can't predict performance with 100% certainty. You can have a solid strategy, you can have a proven process, but you can't guarantee anything. Someone who does is either lying or inexperienced.

But the most critical failure I see is founders going into the search blind. They haven't done the internal work to understand their own business economics. They don't know their customer lifetime value (LTV), their gross margins, or what a profitable customer acquisition cost (CAC) even looks like for them. Without these numbers, you're just guessing. You have no way to judge if a campaign is successful or not. You're flying blind, and that's a surefire way to crash.

So, how do you find the right one? A vetting framework

Alright, so how do you avoid these pitfalls? You need a structured process. This isn't about gut feelings; it's about evidence and strategy. Here's a simple, effective framework for vetting any consultant or agency.

Step 1: Scrutinise their case studies (properly)

This is your number one priority. Don't just glance at the logos on their website. Dig into the actual case studies. Are they detailed? Do they explain the strategy, the challenges, and the results in cold, hard numbers? A good case study should read like a story of a problem being solved.

And most importantly, are they relevant to you? If you're a B2B SaaS company, a case study about a fashion eCommerce brand is pretty much useless. You need to see evidence they've gotten results for businesses similar to yours. I remember one campaign where we got a B2B software client leads for $22 on LinkedIn, and another where we reduced a SaaS client's Cost Per Acquisition from £100 down to just £7. Those are the kind of specific, relevant results you should be looking for. Vague claims like "increased brand awareness" are a massive red flag.

You need a partner who understands the nuances of your industry, and the best way to prove that is with a track record. For anyone serious about this, our vetting framework for B2B agencies in London goes into even more detail on this.

Step 2: The intro call is an audit, not a sales pitch

When you get on a call with a potential consultant, pay close attention to the questions they ask. If they spend the whole time talking about themselves and their amazing process, they're a salesperson. If they spend most of the time asking you sharp, insightful questions about your business, they're a strategist.

A good consultant will want to know about your target customer's pain points, your sales cycle, your profit margins, and your customer LTV. They should be trying to diagnose your situation before they even think about prescribing a solution. We offer a free initial consultation where we actually review a potential client's ad account with them on the call. It gives them a real taste of our expertise and shows them exactly what we'd do differently. This is what you should be looking for – a free strategy session, not a sales pitch. If you walk away from that first call without at least one actionable idea you could implement yourself, they're probably not the one.

Step 3: Understand their process

You need to know how they work. What's their process for developing strategy, for testing creative, for optimising campaigns, and for reporting? It should be a clear, logical system. For instance, we structure campaigns based on the marketing funnel – Top of Funnel (ToFu) for prospecting, Middle of Funnel (MoFu) for retargeting engaged users, and Bottom of Funnel (BoFu) for closing warm leads. It's a proven structure that works.

Ask them to walk you through it. How do they decide which audiences to test first? How do they approach ad copy and creative? What metrics do they report on and why? Their answers should be confident and clear. If it sounds overly complicated or like they're making it up on the spot, that's another red flag.

Before you talk to anyone, can you answer this question?

Here it is: "How much can I afford to spend to acquire a new customer?"

If you don't know the answer, you're not ready to hire a consultant. The answer lies in your Customer Lifetime Value (LTV). This single metric is the foundation of any successful paid advertising strategy. It dictates your budget, your bidding strategy, and your definition of success.

Most people think the goal is to get the lowest Cost Per Lead (CPL) or Cost Per Acquisition (CPA) possible. That's wrong. The goal is to acquire high-value customers profitably. Knowing your LTV tells you exactly how much you can afford to spend. For instance, if your LTV is £10,000, paying £3,333 to acquire that customer is a fantastic deal. But if your LTV is only £400, that same £500 CPA means you're losing money on every sale. See the difference?

Here’s the basic maths:

• -> Average Revenue Per Account (ARPA): What's the average a customer pays you per month?
• -> Gross Margin %: What's your profit margin on that revenue?
• -> Monthly Churn Rate %: What percentage of customers do you lose each month?

The calculation is: LTV = (ARPA * Gross Margin %) / Monthly Churn Rate

To make this easier, here's a simple calculator. Play around with your own numbers to see what your LTV is. This is the most valuable peice of data you can bring to a conversation with a consultant.

Consultant vs. Agency in London: What's the right choice?

This is a common question, and there's no single right answer. It depends on your needs, your budget, and how hands-on you want to be. The London market has everything from huge, well-known agencies in Soho to specialist independent consultants working out of places like Second Home.

An agency typically has a larger team. The benefit is they can offer a wider range of services – paid ads, SEO, content, design, etc. The downside is that you'll often be assigned a more junior account manager to handle your day-to-day. The senior experts who pitched you are often busy pitching the next client. Agencies can be a good fit if you need a full-service team to handle everything and you have a larger budget.

A consultant (or a smaller, specialist consultancy like ours) is different. You're typically working directly with the senior expert. The relationship is more strategic and hands-on. The focus is purely on their area of expertise – in our case, paid advertising. This model works best for founders who want a high-level strategic partner to guide the strategy and execution, rather than just an outsourced team to push buttons. It's often more flexible and can be more cost-effective if all you need is that deep, specialist knowledge.

If you're a SaaS business trying to figure this out, we've written a detailed guide on choosing between a consultant or an agency in London for SaaS marketing which might be helpful.

What should I expect to pay and what results are realistic?

This is the million-dollar question, isn't it? The true answer is "it depends." It depends on your industry, your offer, your target audience, and about a dozen other factors. Anyone who gives you a fixed cost per lead without understanding those things is just guessing.

However, I can give you some realistic ballpark figures for the UK market based on the hundreds of campaigns we've managed. These are for conversions like a lead, a signup, or a subscriber – things that happen relatively quickly.

You're generally looking at a Cost Per Click (CPC) somewhere between £0.50 and £1.50. A decent landing page should convert between 10% and 30% of that traffic. So, the maths looks like this:

• -> Worst case: £1.50 CPC / 10% conversion rate = £15 per conversion
• -> Best case: £0.50 CPC / 30% conversion rate = £1.67 per conversion

So, a realistic range for a lead or signup in the UK is somewhere between £1.60 and £15.00. For eCommerce sales, where conversion rates are lower (usually 2-5%), the range is more like £10 to £75 per sale.

The job of a good consultant is to get you from the high end of that range to the low end. They do this through expert targeting, compelling creative, and ruthless landing page optimisation. It's not magic; it's a methodical process of testing and refinement.

Five red flags that should make you run

I've seen too many London startups get burned by bad actors. To save you some pain and money, here are the biggest red flags to watch out for. If you spot any of these, just walk away.

1. The "Guaranteed Results" Promise. I've mentioned this before but it's worth repeating. It's the number one sign of an amateur or a scam artist. There are too many variables in paid advertising to guarantee anything. A professional talks about targets, projections, and a clear process for getting there, not certainties.
2. The "Secret Sauce". Be wary of anyone who won't be transparent about their methods. If they talk about a "proprietary algorithm" or a "secret strategy" they can't share with you, it's probably because they don't have one. A true expert should be able to clearly explain their entire strategy and rationale to you.
3. They Don't Ask Tough Questions. If a consultant agrees to work with you without deeply questioning your business model, customer, and economics, they're not a strategist. They're an order-taker. A great partner will challenge your assumptions and force you to think critically about your own business before they spend a single pound of your money.
4. One-Size-Fits-All Packages. Your business is unique. Your advertising strategy should be too. If a consultant is trying to sell you a pre-packaged "Gold" or "Platinum" plan without a deep diagnostic, they're not tailoring their approach to your specific needs. Look for a bespoke proposal that directly addresses the challenges and opportunities discussed in your initial call.
5. Reporting on Vanity Metrics. If their reports are full of fluff like impressions, reach, and clicks, but are light on the numbers that actually matter – like CPA, ROAS, and LTV – they are hiding poor performance behind meaningless data. Your report should be a clear, concise summary of how ad spend is translating into actual business growth.

Finding a great consultant isn't easy, but following a good process is the best way to improve your odds. There's a lot more to it, but this is a good start, and we've put together a more detailed London ad consultant vetting guide if you want to dig deeper.

So, you've found a contender. What's next?

Let's say you've gone through this process. You've found a consultant with relevant case studies, they impressed you on the strategy call, and they have a transparent process. What's the final step?

It comes down to trust and fit. Do you feel confident they understand your vision? Do you feel like you could have an open, honest relationship with them? This will be a partnership, so that personal fit is important. You'll be working closely with them, so you need to feel they're on your team.

To make the final decision easier, I've consolidated this entire framework into a simple checklist you can use. Run your top candidates through this, and the right choice should become much clearer.

This is the main advice I have for you:

The process of finding the right partner takes time and effort, but it's one of the most important decisions you'll make for your business's growth. Getting it right means unlocking scalable, predictable revenue. Getting it wrong means months of wasted time and money.

If you're a London-based founder and this approach resonates with you, then perhaps we should have a conversation. We offer a completely free, no-obligation strategy session where we'll audit your current advertising efforts (or lack thereof) and provide you with a clear, actionable plan. It's not a sales pitch; it's a demonstration of the strategic thinking we bring to every client partnership.

If you're ready to stop guessing and start growing, schedule your free consultation today.